Methods of encapsulation
Methods and apparatuses suitable for depositing low hydrogen content, hermetic, thin encapsulation layers at temperatures less than about 300° C. are provided herein. Methods involve pulsing plasma while exposing a substrate to deposition reactants, and post-treating deposited encapsulation films to densify and reduce hydrogen content. Post-treatment methods include periodic exposure to inert plasma without reactants and exposure to ultraviolet radiation at a substrate temperature less than about 300° C.
1. A method of encapsulating a memory device on a substrate, the method comprising:
exposing the substrate having the memory device to a deposition precursor and a reactant at a substrate temperature less than 300° C.; and
igniting a plasma in pulses to deposit an encapsulation layer over the memory device; and
exposing the encapsulation layer to a post-treatment process to form a hermetic encapsulation layer having a hydrogen content less than 15%.
2. The method of claim 1 , wherein the encapsulation layer is selected from the group consisting of silicon nitride, undoped silicon carbide, oxygen-doped silicon carbide, germanium nitride, undoped germanium carbide, and oxygen-doped germanium carbide.
3. The method of claim 1 , wherein the pulses of plasma have a pulse duration between about 0.02 ms and about 5 ms.
4. The method of claim 1 , wherein the plasma is pulsed at a pulsing frequency between about 100 Hz and about 6 Hz.
5. The method of claim 1 , wherein the post-treatment process comprises exposing the substrate to a post-treatment gas and igniting a second plasma without a reactant.
6. The method of claim 5 , wherein the substrate is exposed to the post-treatment gas and the second plasma for a duration between about 10 seconds and about 50 seconds.
7. The method of claim 5 , wherein the post-treatment gas is selected from the group consisting of nitrogen, helium, argon, and combinations thereof.
8. The method of claim 1 , wherein the post-treatment process comprises exposing the substrate to ultraviolet radiation.
9. The method of claim 1 , wherein the memory device is a magnetoresistive random-access memory.
10. The method of claim 1 , wherein the memory device comprises a magnetic tunnel junction.
11. The method of claim 1 , wherein the encapsulation layer is deposited to a thickness between about 50 Å and about 500 Å.
12. The method of claim 1 , wherein the encapsulation layer is deposited by plasma enhanced chemical vapor deposition.
13. The method of claim 1 , wherein the encapsulation layer deposited over the memory device has a step coverage between about 70% and about 90%.
14. The method of claim 1 , wherein the encapsulation layer is a silicon nitride film deposited by exposing the substrate to a silicon-containing precursor and a nitrogen-containing reactant.
15. The method of claim 1 , wherein the encapsulation layer is a silicon carbide film deposited by exposing the substrate to a silicon-and carbon-containing precursor and hydrogen.
16. The method of claim 1 , further comprising prior to depositing the encapsulation layer, heating the substrate to a temperature of about 300° C.
17. A method of encapsulating a memory device on a substrate, the method comprising:
exposing the substrate having the memory device to a deposition precursor and a reactant at a substrate temperature less than 300° C.; and
igniting a plasma to deposit an encapsulation layer by pulsed plasma enhanced chemical vapor deposition over the memory device; and
exposing the encapsulation layer to a post-treatment gas to form a hermetic encapsulation layer having a hydrogen content less than 15%,
wherein the hermetic encapsulation layer comprises silicon nitride, and
wherein the plasma is pulsed between an ON state and an OFF state, wherein the plasma is turned off in the OFF state.
18. The method of claim 1 , wherein the reactant is a non-ammonia gas.
19. The method of claim 1 , wherein the plasma is pulsed between an ON state and OFF state, wherein the plasma is turned off in the OFF state.
20. A method of encapsulating a memory device on a substrate, the method comprising:
providing a substrate having a memory device comprising an exposed surface of non-volatile material selected from the group consisting of cobalt, iron, manganese, nickel, platinum, palladium, ruthenium, and combinations thereof;
exposing the exposed surface to a deposition precursor and a nitrogen-containing reactant at a substrate temperature less than 300° C.;
pulsing a plasma between 0 W and a plasma power density between 0.1 W/cm 2 and about 1.5 W/cm 2 to deposit a encapsulation layer on the exposed surface; and
exposing the encapsulation layer to a post-treatment process to form a hermetic encapsulation layer having a hydrogen content less than 15%.
21. The method of claim 20 , wherein the nitrogen-containing reactant is a non-ammonia gas.
22. The method of claim 1 , wherein the post-treatment process reduces wet etch rate of the hermetic encapsulation layer in 200:1 diluted hydrofluoric acid compared to wet etch rate of the encapsulation layer prior to the post-treatment process.