Method for forming compressive alpha-tantalum on substrates and devices including the same
View Patent ↗A layer of compressive alpha-tantalum is formed on a substrate by depositing a buffer layer on the substrate and depositing a layer of compressive alpha-tantalum on the buffer layer with lattice matching between the layer of compressive alpha-tantalum and the buffer layer. In some embodiments, the method may include depositing buffers layers comprising titanium, niobium, substantially pure aluminum or aluminum-copper alloy.
1. A method of forming a layer of compressive alpha-tantalum on a substrate, comprising:
applying a voltage bias to the substrate while depositing a buffer layer on the substrate; and
depositing the layer of compressive alpha-tantalum on the buffer layer with lattice matching between the layer of compressive alpha-tantalum and the buffer layer.
2. The method according to claim 1 , wherein depositing comprises at least one of the following: sputtering, laser ablation, e-beam and thermal evaporation.
3. The method according to claim 1 , wherein applying a voltage bias comprises applying a voltage ranging from about 0 volts to about −500 volts.
4. The method according to claim 1 , wherein depositing a layer of compressive alpha-tantalum comprises sputtering a layer of compressive alpha-tantalum having thickness from about 10 Angstroms to about 4 micrometers.
5. The method according to claim 1 , wherein the substrate comprises silicon carbide.
6. The method according to claim 1 , wherein the substrate comprises silicon nitride.
7. The method according to claim 1 , wherein depositing a buffer layer comprises depositing a layer of titanium.
8. The method according to claim 7 , wherein depositing a layer of titanium further comprises depositing a layer of titanium having thickness from about 3 monolayers to about 2000 Angstroms.
9. The method according to claim 7 , wherein depositing a layer of titanium further comprises depositing a layer of titanium having thickness from at least about 400 Angstroms.
10. The method according to claim 7 , wherein the layer of titanium orients on the substrate with titanium crystal [100] direction perpendicular to the substrate.
11. The method according to claim 7 , wherein the layer of titanium comprises textured titanium grains.
12. The method according to claim 7 , wherein the lattice matching occurs between the layer of titanium and the layer of compressive alpha-tantalum.
13. The method according to claim 1 , wherein depositing a buffer layer comprises depositing a layer of niobium.
14. The method according to claim 13 , wherein depositing a layer of niobium further comprises depositing a layer of niobium having thickness from about 3 monolayers to about 2000 Angstroms.
15. The method according to claim 7 , wherein depositing a layer of niobium further comprises depositing a layer of niobium having thickness from at least about 200 Angstroms.
16. The method according to claim 1 , wherein depositing a buffer layer comprises depositing a layer of substantially pure aluminum.
17. The method according to claim 16 , wherein depositing a layer of substantially pure aluminum further comprises depositing a layer of substantially pure aluminum having thickness from about 3 monolayers to about 2000 Angstroms.
18. The method according to claim 1 , wherein depositing a buffer layer comprises depositing a layer of aluminum-copper alloy.
19. The method according to claim 18 , wherein depositing a layer of aluminum-copper alloy comprises depositing a layer of aluminum-copper alloy comprising up to about 10% by weight of copper.
20. The method according to claim 19 , wherein depositing a layer of aluminum-copper alloy further comprises depositing a layer of aluminum-copper alloy having thickness from about 3 monolayers to about 2000 Angstroms.
21. The method according to claim 1 , wherein depositing the buffer layer on the substrate and depositing the layer of compressive alpha-tantalum on the buffer layer further comprises maintaining substrate temperatures less than 300° C.