Patent ID: 7916432

Claim:
A thin-film patterning method for a magnetoresistive device, the method comprising the steps of: (a) forming a functional layer on a substrate, wherein the functional layer constitutes a tunneling magnetoresistive (TMR) device having a tunnel barrier layer between ferromagnetic material layers, and the tunnel barrier layer is made of at least one species selected from Al 2 O 3 , MgO and ZnO; (b) forming a first mask layer above the functional layer; (c) forming a patterned resist on the first mask layer; (d) etching the first mask layer by using the resist; (e) removing the resist; (f) forming a second mask layer of Al 2 O 3 by atomic layer deposition, the second mask layer covering a step defined by an edge of the first mask layer, wherein the atomic layer deposition is performed by using reaction between trimethylaluminum (TMA) and H 2 O, (g) dry-etching the second mask layer in a thickness direction of the substrate so as to leave the second mask layer on a side face of the step; (h) removing the first mask layer so as to expose the functional layer under the first mask; and (i) ion milling the functional layer by using the second mask layer.