Method of manufacturing thin film magnetic head

A method of manufacturing a thin-film magnetic head, the head comprising:

• first and second magnetic layers each including a magnetic pole and magnetically coupled to each other, the magnetic poles facing each other with a gap layer in between and positioned to face toward a recording medium;
• and a thin-film coil portion disposed between the two magnetic layers with an insulating film in between;
• the first magnetic layer including a first magnetic layer portion having a first uniform width portion that defines a track width, and a second magnetic layer portion extending over a region where the thin-film coil portion is disposed and magnetically coupled to the first magnetic layer portion, the second magnetic layer including a second uniform width portion formed in a similar position and opposite to the first uniform width portion of the first magnetic layer, the method comprising:
• a first step of forming the first magnetic material layer on the gap layer made of aluminum oxide, and patterning the first magnetic material layer through the use of a first mask made of aluminum oxide by reactive ion etching so as to form at least the first uniform width portion of the first magnetic layer;
• a second step of selectively removing a region of the gap layer excluding a portion that includes to the first uniform width portion of the first magnetic layer by reactive ion etching;
• and
• a third step of patterning a second magnetic material layer by reactive ion etching so as to form at least the second uniform width portion of the second magnetic layer,
• wherein in the first, second, and third steps, the reactive ion etching is performed in a chlorine gas atmosphere at a temperature ranging from 150° C. to 250 ° C.