Patent ID: 7460342

Claim:
A process to modify a magnetic shield in order to reduce sensitivity to external magnetic fields of a magnetic read-write head, comprising: providing an assembly that includes a magnetic read head, centrally disposed between first and second magnetic shields, and a perpendicular magnetic write head disposed between a third magnetic shield and said second magnetic shield; polishing said assembly so that said read and write heads and all three said shields have coplanar lower surfaces that constitute an ABS; forming, on said ABS, a mask, having vertical edges, that covers said read and write heads as well as said magnetic shields except for opposing unprotected areas that extend inwards a first distance from said shields' vertical edges; by means of ion beam milling, removing material from said unprotected areas whereby said third shield acquires a first, centrally located, lower surface, that is coplanar with the ABS, two opposing second lower surfaces that are parallel to, and located a second distance above, the ABS, and opposing sloping surfaces that connect said first and second lower surfaces; and then removing said mask.