Magnetic tunnel junctions and methods of forming the same
A hardmask (HM), for protecting a magnetic tunnel junction (MTJ), may be formed with two portions of HM material: a taper HM portion and a vertical HM portion, separated by one or more dielectric layers. For example, a first etch process may shape the taper HM portion and the vertical HM portion such that a taller HM remains as compared with only using one HM portion. As a result, the MTJ is protected during a second etch process, which results in increased removal efficiency and lower sidewall redeposition. As a result, the taller HM reduces leakage current and increases yields. For example, the MTJ is sufficiently protected during etching such that the MTJ is less likely to experience conductive bridging and thus less likely to suffer from electrical shorts.
1 . A method, comprising:
depositing, over magnetic tunnel junction (MTJ) material, a stack of a first hardmask material, a dielectric material, and a second hardmask material;
patterning the second hardmask material into a vertical hardmask;
patterning the dielectric material based on a profile of the vertical hardmask;
patterning the first hardmask material into a taper hardmask; and
patterning the MTJ material based on a profile of the taper hardmask.
2 . The method of claim 1 , wherein the first hardmask material is deposited to a height in a range from approximately 200 Ångströms (Å) to approximately 400 Å.
3 . The method of claim 1 , wherein the second hardmask material is deposited to a height in a range from approximately 200 Ångströms (Å) to approximately 400 Å.
4 . The method of claim 1 , wherein the dielectric material is deposited to a height in a range from approximately 40 Ångströms (Å) to approximately 60 Å.
5 . The method of claim 1 , wherein patterning the second hardmask material comprises:
performing a chlorine-based etch process.
6 . The method of claim 1 , wherein patterning the dielectric material comprises:
performing a fluorine-based etch process.
7 . The method of claim 1 , wherein patterning the first hardmask material comprises:
performing a chlorine-based etch process that deposits a byproduct of polymer on sidewalls of the first hardmask.
8 . A method, comprising:
patterning a hardmask into a taper profile, wherein a byproduct of polymer is formed on sidewalls of the hardmask during patterning; and
patterning a magnetic tunnel junction (MTJ) using the hardmask with the taper profile, wherein the hardmask is configured as a top electrode after patterning the MTJ.
9 . The method of claim 8 , further comprising:
performing a sidewall cleaning on the MTJ, wherein the hardmask extends across an entire top surface of the MTJ during the sidewall cleaning.
10 . The method of claim 8 , wherein patterning the MTJ comprises:
patterning a fixed layer and a free layer, each comprising a magnetic material; and
patterning a barrier layer comprising a crystalline material.
11 . The method of claim 8 , further comprising:
patterning a bottom electrode based on a profile of the MTJ.
12 . The method of claim 8 , wherein patterning the MTJ comprises:
patterning the MTJ to have a width in a range from approximately 25 nanometers (nm) to approximately 30 nm.
13 . A method, comprising:
depositing, on a magnetic tunnel junction (MTJ) material layer, a first hardmask layer;
depositing a dielectric layer on the first hardmask layer;
depositing a second hardmask layer on the dielectric layer;
patterning the second hardmask layer into an upper hardmask;
patterning the dielectric layer based on a profile of the upper hardmask;
patterning the first hardmask layer into a lower hardmask; and
patterning the MTJ material layer based on a profile of the lower hardmask.
14 . The method of claim 13 , wherein each of the first hardmask layer and the second hardmask layer comprise at least one of a metal, a metal alloy, or a metal nitride.
15 . The method of claim 13 , wherein one or more sidewalls of the upper hardmask form an angle with a bottom surface of the upper hardmask that is included in a range of approximately 85° to approximately 90°.
16 . The method of claim 13 , wherein one or more sidewalls of the lower hardmask form an angle with a bottom surface of the upper hardmask that is included in a range of approximately 75° to approximately 80°.
17 . The method of claim 13 , further comprising:
depositing, prior to patterning the second hardmask layer into the upper hardmask, a stacked mask structure on the second hardmask layer; and
patterning the stacked mask structure into a patterned mask structure,
wherein the second hardmask layer is patterned into the upper hardmask based on a profile of the patterned mask structure.
18 . The method of claim 17 , wherein the stacked mask structure comprises a photoresist layer on a plurality of masking layers.
19 . The method of claim 13 , wherein patterning the first hardmask layer into the lower hardmask comprises performing a chlorine-based etch process that forms a by-product on sidewalls of the lower hardmask, and
wherein the by-product comprises hexagonal boron nitride.
20 . The method of claim 13 , wherein the first hardmask layer is deposited to a first height in a first range from approximately 200 Ångströms (Å) to approximately 400 Å, and
wherein the second hardmask layer is deposited to a second height in a second range from approximately 200 Å to approximately 400 Å.