Method to make a wider trailing pole structure by self-aligned pole trim process
A method for forming a trimmed upper pole piece for a magnetic write head, said pole piece having a tapered profile that is widest at its trailing edge. Such a pole piece is capable of writing narrow tracks with sharply and well defined patterns and minimal overwriting of adjacent tracks. The present method produces the necessary taper by using NiCr, NiFeCr, Rh or Ru as write gap filling materials which have an etch rate which is substantially equal to the etch rate of the other layers forming the pole piece and are highly corrosion resistant. As a result, the write gap does not protrude to mask the effects of the ion-beam etch used to form the taper.
1. A method for forming a trimmed upper pole piece for a magnetic write head, said upper pole piece being of tapered profile and varying from greatest width at a trailing edge to smallest width at a leading edge, comprising:
providing a magnetic shield layer, said shield layer being formed of material having a first ion-beam etch rate;
forming on said shield layer a write gap layer, said layer being formed of material having a second ion-beam etch rate;
forming on said write gap layer a seed layer, said seed layer having a third ion-beam etch rate;
forming on said seed layer a plated upper pole portion, said plated pole portion being formed with a tapered initial profile by a plating process and said plated pole portion being formed of material having a fourth ion-beam etch rate, wherein said first, second, third and fourth ion-beam etch rates are substantially equal;
using an ion-beam etching process, trimming said shield layer, said write gap layer, said seed layer and said pole portion to form an upper pole piece of final tapered profile whose width is maximum at its trailing edge and minimum at its leading edge.
2. The method of claim 1 wherein the shield layer is formed of CoNiFe.
3. The method of claim 1 wherein the write gap layer is a layer of NiCr of 40% Cr by atomic percentage.
4. The method of claim 3 wherein the NiCr is formed to a thickness of between approximately 500 and 1500 angstroms.
5. The method of claim 1 wherein the write gap layer is a layer of NiFeCr formed to a thickness between approximately 500 and 1500 angstroms.
6. The method of claim 1 wherein the write gap layer is a layer of Ru formed to a thickness between approximately 500 and 1500 angstroms.
7. The method of claim 1 wherein the write gap layer is a layer of Rh formed to a thickness between approximately 500 and 1500 angstroms.
8. The method of claim 1 wherein the seed layer is a layer of CoFeN formed to a thickness between approximately 1000 and 3000 angstroms.
9. The method of claim 1 wherein the initially formed plated pole portion is a plated layer of CoNiFe, having a profile which tapers from a maximum width between approximately 0.20 and 0.40 microns at its trailing edge, to a minimum width between approximately 0.45 and 0.65 microns at its leading edge and formed to a thickness of between approximately 35,000 and 40,000 angstroms.
10. The method of claim 1 wherein the ion-beam etch uses a beam of Ar ions at a voltage of approximately 700 volts and a current of approximately 800 mA.
11. The method of claim 1 wherein the ion-beam etching (IBE) process further comprises:
using a high angle IBE to remove portions of the seed layer laterally disposed to either side of the plated pole portion, leaving only a portion of the seed layer remaining beneath said plated pole portion;
using a shallow angle IBE to create a pedestal in the shield layer and trimming, thereby, the write gap layer to the width of said pedestal;
using a high angle IBE to produce a pedestal of substantially uniform width, and a sequentially layered write gap layer, seed layer and plated pole portion formed with a final tapered profile.
12. The method of claim 11 wherein the final profile tapers from a maximum width of between approximately 0.30 and 0.40 microns to a minimum width of between approximately 0.15 and 0.25 microns.