METHOD FOR MANUFACTURING HIGH DENSITY NON-VOLATILE MAGNETIC MEMORY
First Claim
1. A method for fabricating thin film magnetic memory cells on a wafer comprising:
- depositing a stack of layers for a magnetic memory device on a substrate;
depositing a lower dielectric layer over the stack of layers for a magnetic memory device;
depositing a metal layer over the lower dielectric layer;
depositing an upper dielectric material layer over the metal layer;
patterning a first line mask of parallel lines of material;
forming parallel lines in the upper dielectric material by etching through the upper dielectric material layer using the first line mask;
patterning a second line mask over the parallel lines of upper dielectric material, the second line mask including parallel lines arranged orthogonally to the parallel lines of upper dielectric material and overlapping the parallel lines of upper dielectric material;
forming pads of upper dielectric material by etching through the parallel lines of upper dielectric layer using the second line mask; and
forming pillars of layers for the magnetic memory device on the substrate by executing a series of etching processes that successively transfer a shape of the pads of upper dielectric material into layers below the pads of upper dielectric material.
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Abstract
Methods of fabricating MTJ arrays using two orthogonal line patterning steps are described. Embodiments are described that use a self-aligned double patterning method for one or both orthogonal line patterning steps to achieve dense arrays of MTJs with feature dimensions one half of the minimum photo lithography feature size (F). In one set of embodiments, the materials and thicknesses of the stack of layers that provide the masking function are selected so that after the initial set of mask pads have been patterned, a sequence of etching steps progressively transfers the mask pad shape through the multiple mask layer and down through all of the MTJ cell layers to the form the complete MTJ pillars. In another set of embodiments, the MTJ/BE stack is patterned into parallel lines before the top electrode layer is deposited.
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Citations
15 Claims
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1. A method for fabricating thin film magnetic memory cells on a wafer comprising:
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depositing a stack of layers for a magnetic memory device on a substrate; depositing a lower dielectric layer over the stack of layers for a magnetic memory device; depositing a metal layer over the lower dielectric layer; depositing an upper dielectric material layer over the metal layer; patterning a first line mask of parallel lines of material; forming parallel lines in the upper dielectric material by etching through the upper dielectric material layer using the first line mask; patterning a second line mask over the parallel lines of upper dielectric material, the second line mask including parallel lines arranged orthogonally to the parallel lines of upper dielectric material and overlapping the parallel lines of upper dielectric material; forming pads of upper dielectric material by etching through the parallel lines of upper dielectric layer using the second line mask; and forming pillars of layers for the magnetic memory device on the substrate by executing a series of etching processes that successively transfer a shape of the pads of upper dielectric material into layers below the pads of upper dielectric material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for fabricating thin film magnetic memory cells on a wafer comprising:
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depositing a stack of layers for a magnetic memory device on a substrate; depositing a hard mask layer over the stack of layers for a magnetic memory device; patterning a first line mask of parallel lines of material; forming parallel lines of hard mask material by etching through the hard mask layer using the first line mask; etching through the stack of layers for a magnetic memory device using the parallel lines of hard mask material as a mask to form lines of the layers for the magnetic memory device under the parallel lines of hard mask material; depositing a conformal layer of an encapsulation material over the parallel lines of hard mask material and onto sidewalls of the lines of layers for the magnetic memory device under the parallel lines of hard mask material; depositing a layer of fill material over the conformal layer of an encapsulation material; planarizing the wafer to expose parallel lines of hard mask material; depositing a top electrode layer over the wafer and in contact with the expose parallel lines of hard mask material; depositing a lower dielectric layer over the top electrode layer; forming parallel lines in the lower dielectric material using a second line mask with parallel lines of material orthogonal to the parallel lines in the first line mask; forming parallel lines in the top electrode layer using the parallel lines in the lower dielectric material as a mask; and removing material in layers for the magnetic memory device that are not covered by the parallel lines in the top electrode layer to form separate pads of the layers for the magnetic memory device under the parallel lines of the top electrode layer material. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification