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Multiply spin-coated ultra-thick hybrid hard mask for sub 60nm MRAM devices

  • US 10,522,750 B2
  • Filed: 02/19/2018
  • Issued: 12/31/2019
  • Est. Priority Date: 02/19/2018
  • Status: Active Grant
First Claim
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1. A method for etching a magnetic tunneling junction (MTJ) structure, the method comprising:

  • providing a MTJ stack on a substrate;

    depositing a metal hard mask layer having a first thickness on the MTJ stack;

    depositing a dielectric hard mask layer on the metal hard mask layer;

    forming a hybrid hard mask on the dielectric hard mask layer wherein the hybrid hard mask comprises a plurality of spin-on carbon layers alternating with a plurality of spin-on silicon layers, wherein a topmost layer of the hybrid hard mask is a silicon layer;

    forming a photo resist pattern on the hybrid hard mask;

    first etching portions of the topmost silicon layer of the hybrid hard mask exposed by the photo resist pattern using a first etching chemistry;

    thereafter second etching the plurality of spin-on carbon layers and the plurality of spin-on silicon layers of the hybrid hard mask exposed by the photo resist pattern using a second etching chemistry, wherein the second etching chemistry etches away the photo resist pattern; and

    thereafter etching portions of each of the dielectric hard mask, the metal hard mask, and the MTJ stack exposed by the hybrid hard mask to form a MTJ device and overlying top electrode, wherein the metal hard mask layer remaining has a second thickness no less than 80% of the first thickness.

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