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US 7,252,774 B2Granted
Selective chemical etch method for MRAM soft layers
AssigneeInternational Business Machines Corporation
InventorsEugene J. O'Sullivan, David Abraham
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Abstract
An etching process is employed to selectively pattern the exposed magnetic film layer of a magnetic thin film structure. The magnetic structure to be etched includes at least one bottom magnetic film layer and at least one top film layer which are separated by a tunnel barrier. The etching process employs various etching steps that selectively remove various layers of the magnetic thin film structure stopping on the tunnel barrier layer.
Claims20
A method of selectively patterning a magnetic film structure comprising the steps of:
- (a) providing a magnetic structure comprising at least one bottom magnetic film layer and at least one top magnetic film layer, wherein said at least one top and said at least one bottom magnetic film layers are separated by a tunnel barrier layer, and said at least one top magnetic film layer having a passivating layer located thereon;
- (b) forming a patterned resist on said passivating layer, wherein a portion of said passivating layer is exposed;
- (c) selectively etching said exposed portion of said passivating layer by a reactive-ion etching process to expose a portion of said at least one top magnetic film layer;
- and
- (d) selectively etching said exposed portion of said at least one top magnetic film layer by a wet etch process which includes an etchant solution comprising a surfactant inhibitor and at least one weakly adsorbing acid stopping on said tunnel barrier layer.
2 more elements
Dependencies are inferred from the claim text.