Deposition of LiCoO
View Patent ↗In accordance with the present invention, deposition of LiCoO 2 layers in a pulsed-dc physical vapor deposition process is presented. Such a deposition can provide a low-temperature, high deposition rate deposition of a crystalline layer of LiCoO 2 with a desired ( 101 ) or ( 003 ) orientation. Some embodiments of the deposition addresses the need for high rate deposition of LiCoO 2 films, which can be utilized as the cathode layer in a solid state rechargeable Li battery. Embodiments of the process according to the present invention can eliminate the high temperature (>700° C.) anneal step that is conventionally needed to crystallize the LiCoO 2 layer. Some embodiments of the process can improve a battery utilizing the LiCoO 2 layer by utilizing a rapid thermal anneal process with short ramp rates.
1. A method of depositing a LiCoO 2 layer, comprising:
placing a substrate in a reactor;
flowing at least an inert gas through the reactor;
applying pulsed DC power to a sputter target comprising LiCoO 2 ;
positioning said target opposite said substrate;
forming a layer of LiCoO 2 over said substrate; and
applying rapid thermal annealing to said substrate and LiCoO 2 layer to a temperature of less than about 700° C. for a period of time of less than about 10 minutes.
2. The method of claim 1 , wherein said rapid thermal annealing step is performed at a sufficiently low temperature in conjunction with a sufficiently short period of time thus providing a sufficiently low thermal budget, which is applied to low temperature substrate material without melting it.
3. The method of claim 1 , wherein said substrate comprises, at least in part, a material selected from the group of silicon, polymers, glasses, ceramics, stainless steel, and metals.
4. The method of claim 1 , further comprising depositing a platinum layer on said substrate.
5. The method of claim 1 , further comprising depositing an electrically conducting layer on the substrate.
6. The method of claim 1 , further comprising applying a RF bias to said substrate while applying pulsed DC power to said sputter target.
7. The method of claim 1 , wherein said LiCoO 2 layer comprises, at least in part, a crystalline structure.
8. The method of claim 1 , wherein said LiCoO 2 layer comprises, at least in part, a crystalline structure and a preferred crystallographic orientation in the (101) plane.
9. The method of claim 1 , wherein said LiCoO 2 layer comprises, at least in part, a crystalline structure and a preferred crystallographic orientation in the (003) plane.
10. The method of claim 1 , wherein said LiCoO 2 layer comprises a grain size of between about 500 Å and about 3000 Å.
11. The method of claim 1 , further comprising preheating said substrate to a temperature of up to about 200 ° C. prior to depositing said LiCoO 2 layer.
12. The method of claim 1 , further comprising preheating said substrate prior to depositing said LiCoO 2 layer; said depositing of LiCoO 2 occurring without applying active substrate heating.
13. The method of claim 1 , further comprising depositing an oxide layer on said substrate.
14. The method of claim 13 , wherein said oxide layer comprises a silicon dioxide layer.
15. The method of claim 1 , further comprising depositing said LiCoO 2 layer at a rate greater than about 1 μm per hour.
16. The method of claim 1 wherein said sputter target comprises a ceramic LiCoO 2 sputter target with a resistance measured across about 4 cm of its surface of less than about 500 kΩ.
17. A method of depositing a lithium metal oxide layer, comprising:
placing a substrate in a reactor;
flowing at least an inert gas through the reactor;
applying pulsed DC power to a sputter target comprising lithium metal oxide;
positioning said target opposite said substrate;
forming a layer of said lithium metal oxide over said substrate; and
applying rapid thermal annealing to said substrate and lithium metal oxide layer to a temperature of less than about 700° C. for a period of time of less than about 10 minutes.
18. The method of claim 17 , wherein said rapid thermal annealing step is performed at a sufficiently low temperature in conjunction with a sufficiently short period of time thus providing a sufficiently low thermal budget, which is applied to low temperature substrate material without melting it.
19. The method of claim 17 , wherein said substrate comprises, at least in part, a material selected from the group of silicon, polymers, glasses, ceramics, stainless steel, and metals.
20. The method of claim 17 , further comprising depositing a platinum layer on said substrate.
21. The method of claim 17 , further comprising depositing an electrically-conducting layer on the substrate.
22. The method of claim 17 , further comprising applying a RF bias to said substrate while applying pulsed DC power to said sputter target.
23. The method of claim 17 , wherein said lithium metal oxide layer comprises, at least in part, a crystalline structure.
24. The method of claim 17 , wherein said lithium metal oxide layer comprises, at least in part, a crystalline structure and a preferred crystallographic orientation in the (101) plane.
25. The method of claim 17 , wherein said lithium metal oxide layer comprises, at least in part, a crystalline structure and a preferred crystallographic orientation in the (003) plane.
26. The method of claim 17 , wherein said lithium metal oxide layer comprises a grain size of between about 500 Å and about 3000 Å.
27. The method of claim 17 , further comprising preheating said substrate to a temperature of up to about 200° C. prior to depositing said lithium metal oxide layer.
28. The method of claim 17 , further comprising preheating said substrate prior to depositing said lithium metal oxide layer; said depositing of lithium metal oxide occurring without applying active substrate heating.
29. The method of claim 17 , further comprising depositing an oxide layer on said substrate.
30. The method of claim 29 , wherein said oxide layer comprises a silicon dioxide layer.
31. The method of claim 17 , further comprising depositing said lithium metal oxide layer at a rate greater than about 1 μm per hour.
32. The method of claim 17 , wherein said sputter target comprises a ceramic lithium metal oxide sputter target with a resistance measured across about 4 cm of its surface of less than about 500 kΩ.