A magnetic write head has a plated coil with narrow pitch and is suitable for writing at high frequencies on magnetic media with high coercivity. The narrow pitch is obtained without such disadvantages as overplating that has adversely affected prior art attempts to produce such narrow pitches. The process that produces the magnetic write head is characterized by an RIE plasma etch using O2/N2 to etch plating trenches into a baked layer of photoresist with the ratio of gases being 5/45 sccm so that a dilute O2 concentration does not create unwanted side etching of the plating trenches. In addition, a Cu seed layer is coated with an insulating layer of Al2O3 which redeposits on the trench sidewalls to inhibit redeposition of any Cu from the seed layer and prevent outward growth of the plated Cu that would result in overplating.