An attenuating phase shifting mask for forming contact holes in a layer of negative resist, a method of forming the mask, and a method of forming the contact holes are described. The mask is formed from a mask blank having a layer of attenuating phase shifting material formed on a transparent mask blank. The attenuating phase shifting material has a transmittance of greater than 20% and between about 20% and 50% for light having a wavelength of 193 nanometers. The mask is a dark tone mask having mask elements formed of the attenuating phase shifting material at the locations of the mask corresponding to the locations of the contact holes. The mask is used to expose a layer of negative resist which is then developed to form the contact holes.