Method to fabricate a magnetic head including ion milling of read gap using dual layer hard mask

A method to manufacture a magnetic head, the method comprising:

• providing a first layered structure including a magnetic layer, a first hard mask layer immediately adjacent and contacting the magnetic layer, a second hard mask layer immediately adjacent and contacting the first hard mask layer;
• and a first stepping layer immediately adjacent and contacting the second hard mask layer;
• etching through the first stepping layer to create a sidewall of the first stepping layer;
• depositing a mask-width definition layer on and adjacent to the sidewall, until a mask-width definition layer thickness is achieved adjacent to the sidewall;
• removing the mask-width definition layer except on the sidewall;
• removing the first stepping layer;
• etching away the second hard mask layer except for a remainder of the second hard mask layer beneath the mask-width definition layer;
• etching away the first hard mask layer around the remainder of the second hard mask layer to define a remainder of the first hard mask layer beneath the remainder of the of the second hard mask layer, to form a dual layer hard mask comprising the remainder of the second hard mask layer and the remainder of the first hard mask layer;
• and
• ion milling the magnetic layer around the dual hard mask.