Diamond-like carbon hardmask for MRAM
Techniques for MRAM patterning using a diamond-like carbon hardmask are provided. In one aspect, a method of forming an MRAM device includes: forming an MRAM stack on a substrate; depositing a metal hardmask layer on the MRAM stack; depositing a diamond-like carbon layer on the metal hardmask layer; forming a patterned resist on the diamond-like carbon layer; patterning the diamond-like carbon layer using the patterned resist to form a diamond-like carbon pillar; patterning the metal hardmask layer using the diamond-like carbon pillar to form a patterned metal hardmask; and patterning the MRAM stack into an MRAM pillar using the patterned metal hardmask to form the MRAM device. An MRAM device is also provided.
1. A method of forming a magnetoresistive random access memory (MRAM) device, the method comprising the steps of:
forming an MRAM stack on a substrate, wherein the MRAM stack directly contacts at least a portion of the substrate;
depositing a metal hardmask layer directly on the MRAM stack;
depositing a diamond-like carbon layer directly on the metal hardmask layer;
incorporating at least one metal during deposition of the diamond-like carbon layer such that the diamond-like carbon layer is electrically conductive;
forming a patterned resist on the diamond-like carbon layer;
patterning the diamond-like carbon layer using the patterned resist to form a diamond-like carbon pillar;
patterning the metal hardmask layer using the diamond-like carbon pillar to form a patterned metal hardmask; and
patterning the MRAM stack into an MRAM pillar using the patterned metal hardmask to form the MRAM device.
2. The method of claim 1 , further comprising the step of:
fully removing the diamond-like carbon pillar after patterning the MRAM stack.
3. The method of claim 1 , wherein the substrate contains a metal landing pad, the method further comprising the step of:
forming the MRAM stack on the substrate over the metal landing pad.
4. The method of claim 1 , wherein the MRAM stack comprises a magnetic tunnel junction (MTJ) element.
5. The method of claim 4 , wherein the MTJ element comprises:
a first magnetic metal layer;
a tunnel barrier disposed on the first magnetic metal layer; and
a second magnetic metal layer disposed on the tunnel barrier.
6. The method of claim 1 , wherein the metal hardmask layer comprises tantalum nitride, titanium nitride, tungsten, and combinations thereof.
7. The method of claim 1 , wherein the diamond-like carbon material comprises amorphous carbon.
8. The method of claim 7 , wherein the diamond-like carbon material comprises from about 10 atomic percent hydrogen to about 50 atomic percent hydrogen and ranges therebetween.
9. The method of claim 7 , wherein the diamond-like carbon material comprises less than about 1 atomic percent hydrogen.
10. The method of claim 1 , wherein the diamond-like carbon material is deposited to a thickness of from about 100 Å to about 300 Å and ranges therebetween.
11. The method of claim 1 , wherein the at least one metal is selected from the group consisting of: copper, titanium, and combinations thereof.