the amorphous carbon followed by a layer of photodefinable material which is deposited over the array portion of the substrate the photodefinable material is removed along with the inorganic hard mask overlaying the periphery a portion of the amorphous carbon layer is etched in the exposed periphery the inorganic hard mask is removed and normal high aspect ratio etching continues the amount of amorphous carbon layer remaining in the periphery results in a more uniform mask height between the array and periphery at the end of high aspect ratio etching the more uniform mask height mitigates twisting at the edge of the array application_number US 75871407 A description in the following detailed description of the embodiments reference is made to the accompanying drawings that form a part hereof and in which are shown by way of illustration and not by way of limitation specific embodiments in which the invention may be practiced it is to be understood that other embodiments may be utilized and that logical mechanical and electrical changes may be made without departing from the spirit and scope of the present invention the term u2018 substrate u2019 is to be understood as a semiconductor based material including silicon silicon on insulator soi or silicon on sapphire sos technology doped and undoped semiconductors epitaxial layers of silicon supported by a base semiconductor foundation and other semiconductor structures further in.