Sputtering target of Li
View Patent ↗A method of forming a lithium orthophosphate sputter target or tile and resulting target material is presented. The target is fabricated from a pure lithium orthophosphate powder refined to a fine powder grain size. After steps of consolidation into a ceramic body, packaging and degassing, the ceramic body is densified to high density, and transformed into a stable single phase of pure lithium orthophosphate under sealed atmosphere. The lithium orthophosphate target is comprised of a single phase, and can preferably have a phase purity greater than 95% and a density of greater than 95%.
1. A method of forming a target, comprising:
providing a lithium orthophosphate powder;
refining the powder to a grain size of equal to or less than 75 microns;
applying cold isostatic pressure processing to form a body;
degassing said body;
applying hot isostatic pressure processing to said body to form a dense body of single-phase lithium orthophosphate; and
finishing said dense body to form a sputter target comprising a single phase comprising a phase purity greater than 90% and a density of greater than 90%.
2. The method of claim 1 , wherein said sputter target comprises a polycrystalline Li 3 PO 4 phase.
3. The method of claim 1 , wherein said sputter target comprises a single crystal morphology of Li 3 PO 4 .
4. The method of claim 1 , wherein said sputter target comprises a glassy Li 3 PO 4 phase.
5. The method of claim 1 , wherein said sputter target comprises a phase purity of greater than 95%.
6. The method of claim 1 , wherein said sputter target comprises a density greater than 95%.
7. The method of claim 1 , wherein said sputter target comprises a density between 95% and 99%.
8. The method of claim 1 , further comprising using said target inside a vacuum sputter deposition tool.
9. The method of claim 1 , further comprising mixing small amounts of lithium oxide powder with said lithium orthophosphate powder prior to said refining the powder step.
10. The method of claim 1 , further comprising refining said lithium orthophosphate powder to a mesh size of 250 mesh.
11. The method of claim 1 , further comprising densifying the refined powder to approximately 50% density using the cold isostatic pressure process.
12. The method of claim 1 , further comprising degasifying said body at a temperature between 400° C. to 550° C.
13. The method of claim 1 , further comprising applying said hot isostatic pressure processing at pressures above 10 kpsi.
14. The method of claim 13 , further comprising performing said hot isostatic pressure processing at a temperature less than about 850° C. for about 2 hours.
15. A lithium orthophosphate sputter target comprising a single phase comprising a phase purity greater than 90% and a density greater than 90%.
16. The target of claim 15 , wherein said phase purity is greater than 95%.
17. The target of claim 15 , wherein said density is greater than 95%.
18. The target of claim 15 , wherein said density is between 95% and 99%.
19. The target of claim 15 , wherein said phase purity is between 95% and 99%.
20. The target of claim 15 , wherein said phase purity is greater than 99%.
21. The target of claim 15 , comprising a polycrystalline Li 3 PO 4 phase.
22. The target of claim 15 , comprising a single crystal morphology of Li 3 PO 4 .
23. The target of claim 15 , comprising a glassy Li 3 PO 4 phase.