Selective chemical removal of coil seed-layer in thin film head magnetic transducer
AssigneeSeagate Technology LLC
InventorsUri Cohen, Wei C. Hsie
Life of this patent
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Abstract
The seed-layer, or metallization layer, used to form the coil winding in a thin film head (TFH) by electrodeposition, is removed from between individual winding turns by selective etching with an etchant which preferentially, or selectively, attacks the seed-layer while leaving the coil winding, insulation, and gap materials essentially intact. A suitable combination of compatible materials which can be used as the seed-layer, coil winding, and etchant, respectively, in practicing this invention comprises nickel-iron Permalloy, copper, and a mixture of nitric acid and phosphoric acid diluted in pure water. Other combinations of materials and types of etching processes suitable for this invention are also disclosed.
Claims26
A process for forming a thin film magnetic transducer head, including the steps of:
- depositing on a substrate a first metallic conductive seed-layer;
- forming a mask pattern on the seed-layer defining the shape of a coil winding for the head;
- and depositing through the mask pattern and onto the exposed seed-layer a second metallic conductive material, chemically distinct from the seed-layer, to form a coil winding, wherein the improvement comprises:
- (a) depositing a seed-layer comprising a first metallic conductive material;
- (b) after forming the mask pattern of the coil winding on the seed-layer, depositing as defined by the mask pattern a second metallic conductive material, chemically distinct from the seed-layer, to form the coil winding;
- (c) after depositing the coil winding, removing substantially all residue of the mask pattern to expose the seed-layer;
- and
- (d) selectively etching the exposed seed-layer by subjecting the seed-layer and coil-winding to a selective etchant, which etchant removes the first metallic conductive seed-layer material at a significantly higher rate than the second metallic conductive coil winding material to thereby remove the seed-layer from between individual coil winding turns while leaving the coil winding essentially intact.
A process for forming a thin film magnetic transducer head, having one or more coil winding layers, the formation of each coil winding layer including the steps of:
- depositing on a substrate a first metallic conductive seed-layer;
- forming a mask pattern on the seed-layer defining the shape of a coil winding for the head;
- and depositing through the mask pattern and onto the exposed seed-layer a second metallic conductive material, chemically distinct from the seed-layer, to form a coil winding, wherein the improvement comprises:
- (a) depositing a seed-layer comprising a first metallic conductive material;
- (b) after forming the mask pattern of the coil winding on the seed-layer, depositing as defined by the mask pattern a second metallic conductive material, chemically distinct from the seed-layer, to form the coil winding;
- (c) after depositing the coil winding, removing substantially all residue of the mask pattern to expose the seed-layer;
- (d) selectively etching the exposed seed-layer by subjecting the seed-layer and coil-winding to a selective etchant, which etchant removes the first metallic conductive seed-layer material at a significantly higher rate than the second metallic conductive coil winding material to thereby remove the seed-layer from between individual coil winding turns while leaving the coil winding essentially intact;
- and
- (e) for each additional coil winding layer, forming an additional insulation layer over the area of the coil winding formed in accordance with steps (a) to (d) and repeating in sequence steps (a) to (d).
Dependencies are inferred from the claim text.