fig8 a shows top down view of a mask with first phase shift regions comprised of unit cells 801 in a random contact pattern with u201c regulator phase feature u201d 801 added to regulate the intensity fig8 b is a top down image of a mask with first phase shift regions comprised of unit cells in a random simulated contact hole 816 pattern with u201c regulator phase feature u201d 801 added to regulate the intensity the black background is 180 deg phase shifted quartz all the grey blocks are 0 deg phase shifted quartz u201c phase features u201d the white features are the simulated contact hole opening they appeared displaced from the contact location and vary in sizes as no proximity correction is done with this illustration fig8 a shows the first region comprised of a double cell 822 comprised of at least two unit cells are joined and at least a first separate unit cell 812 the double cell 822 and the first unit cell 812 are separated by at least a regulator feature 814 or 801 fig9 pictorially illustrates an optical system 150 that uses a chromeless phase shift mask of an embodiment of the present invention generally illumination source 155 is a lamp which emits commonly used frequencies such as i line 365 nanometers however other sources of illumination can be used such as excimer laser with.