Patent ID: 8027125

Claim:
A method of preparing a mold shape for depositing a magnetic material therein during the formation of a main pole layer in a perpendicular magnetic recording (PMR) write head, comprising: (a) sequentially depositing a reactive ion etch (RIE) resistant layer and an insulation layer on a substrate; (b) coating a first photoresist layer on the insulation layer and patterning said first photoresist layer to form a rectangular shaped opening that uncovers a portion of the insulation layer; (c) performing a first RIE etch step to transfer said rectangular shaped opening through the insulation layer and stopping on the RIE resistant layer to form a rectangular trench in the insulation layer, said rectangular trench has two long sides aligned in a direction perpendicular to an intended ABS plane, and said rectangular trench has a width that corresponds to a track width in a write pole portion of the main pole layer and has sidewalls with a certain beveled angle such that a top portion of the rectangular trench is larger than a bottom portion of said rectangular trench; (d) removing said first photoresist layer; (e) coating a second photoresist layer on the insulation layer and patterning said second photoresist layer to form a yoke shaped opening that is partially superimposed over said rectangular trench and uncovers an end of the rectangular trench opposite the intended ABS plane, said yoke shaped opening has a plurality of sides wherein two sides that define a portion of a yoke adjacent to the pole portion converge at a point above said rectangular trench and said point of convergence is positioned between the intended ABS plane and a intended neck transition point where the yoke adjoins a write pole in the main pole layer; (f) performing a second RIE step to transfer said yoke shaped opening through the insulation layer and stopping on the RIE resistant layer to form a yoke shaped opening having essentially vertical sidewalls in the insulation layer, said second RIE step removes a portion of the trench opening exposed by the yoke shaped opening such that the yoke shaped opening adjoins the rectangular trench at a neck transition point along each of the two long sides of the rectangular trench; and (g) removing the second photoresist layer.