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MRAM fabrication method with sidewall cleaning

  • US 8,574,928 B2
  • Filed: 04/10/2012
  • Issued: 11/05/2013
  • Est. Priority Date: 04/10/2012
  • Status: Active Grant
First Claim
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1. A method for fabricating thin film magnetic memory cells on a wafer comprising:

  • depositing a stack of layers for a magnetic tunnel junction memory device including a top electrode, a bottom electrode and an upper magnetic layer and a lower magnetic layer separated by a barrier layer;

    patterning the stack of layers to form a plurality of pillars with an upper surface being the top electrode and the upper magnetic layer and the barrier layer having exposed sidewalls, the patterning resulting in re-deposition material being deposited on the exposed sidewalls of the upper magnetic layer and the barrier layer;

    vertically depositing a layer of a first dielectric material over the pillars including the top electrodes and on the sidewalls of the upper magnetic layers and the barrier layers having re-deposition material deposited thereon;

    physically etching the pillars so that the top surface of the pillars is etched faster than other surfaces of the pillar, the etching continuing until the first dielectric material has been removed from the top electrode and first dielectric material along with the re-deposited material has been removed the sidewalls of the upper magnetic layer and the barrier layer;

    depositing an oxygen-free second dielectric material over the pillars on the wafer;

    depositing an inter-layer dielectric (ILD) material over the pillars on the wafer, the ILD material having a higher etching rate in a first selected dry etching process than the second dielectric material;

    planarizing the wafer using chemical-mechanical polishing (CMP);

    patterning trench lines across the top electrodes, the patterning including using the first selected dry etching process to remove inter-layer dielectric (ILD) material down to the second dielectric material which acts as an etch stop;

    removing second dielectric material to expose the top electrodes in the pillars using a second selected dry etching process; and

    depositing metal over the exposed top electrodes in the trench lines.

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