Redeposition control in MRAM fabrication process
First Claim
1. A method of fabricating memory cells comprising:
- patterning a set of landing pads for the memory cells on a wafer;
depositing a dielectric film over the wafer;
etching selected holes through the dielectric film using a mask having gaps positioned over the dielectric film above a selected central area of an upper surface of each landing pad, the etching leaving the selected central area of the upper surface of each landing pad exposed;
depositing metal over the wafer and into the holes in the dielectric film to form metal studs in electrical contact with the upper surface of each landing pad; and
patterning a multi-layered memory cell pillar including a bottom electrode over each metal stud so that the metal stub provides electrical connection between the bottom electrode and the landing pad under the metal stud.
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Accused Products
Abstract
Methods and structures are described to reduce metallic redeposition material in the memory cells, such as MTJ cells, during pillar etching. One embodiment forms metal studs on top of the landing pads in a dielectric layer that otherwise covers the exposed metal surfaces on the wafer. Another embodiment patterns the MTJ and bottom electrode separately. The bottom electrode mask then covers metal under the bottom electrode. Another embodiment divides the pillar etching process into two phases. The first phase etches down to the lower magnetic layer, then the sidewalls of the barrier layer are covered with a dielectric material which is then vertically etched. The second phase of the etching then patterns the remaining layers. Another embodiment uses a hard mask above the top electrode to etch the MTJ pillar until near the end point of the bottom electrode, deposits a dielectric, then vertically etches the remaining bottom electrode.
76 Citations
4 Claims
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1. A method of fabricating memory cells comprising:
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patterning a set of landing pads for the memory cells on a wafer; depositing a dielectric film over the wafer; etching selected holes through the dielectric film using a mask having gaps positioned over the dielectric film above a selected central area of an upper surface of each landing pad, the etching leaving the selected central area of the upper surface of each landing pad exposed; depositing metal over the wafer and into the holes in the dielectric film to form metal studs in electrical contact with the upper surface of each landing pad; and patterning a multi-layered memory cell pillar including a bottom electrode over each metal stud so that the metal stub provides electrical connection between the bottom electrode and the landing pad under the metal stud. - View Dependent Claims (2, 3, 4)
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Specification