Patent ID: 7655388

Claim:
A method for projecting patterns onto a semiconductor substrate comprising: providing an illumination source; providing a phase shift mask that has a first phase shift region and a second phase shift region, the first shift region is disposed on a first layer of the mask and the second phase shift region on a second layer of the mask, wherein the first and second phase shift regions are out of phase, the first phase shift region comprises a continuous unit cell, wherein the unit cell comprises a center section and extension sections, the extension sections are contiguous to and extend outwards from the center section, the distinct extension sections having a same width as the center section, the second phase shift region is adjacent to the unit cell in the first phase shift region; and projecting light from the illumination source through the phase shift mask onto the semiconductor substrate, wherein destructive interference between the first and second phase shift regions due to shape of the unit cell creates a desired exposure pattern on a photosensitive layer on the substrate corresponding to about the center section.