DEPOSITION OF LiCoO2

• US 20070125638A1
• Filed: 11/07/2006
• Published: 06/07/2007
• Est. Priority Date: 12/08/2004
• Status: Active Grant

• Current Assignee: Sapurast Research LLC
• Original Assignee: Infinite Power Solutions, Inc. (Apple Inc.)
• Inventors: Shao, May, Zhang, Hongmei, Demaray, Richard
• Granted Patent: US 7,959,769 B2
• Time in Patent Office: Days
• US Class Current: 204/192.150
• CPC Class Codes: C23C 14/08 Oxides C23C14/10 takes precedence
• CPC Class Codes: C23C 14/345 using substrate bias
• CPC Class Codes: C23C 14/35 by application of a magnetic field, e.g. magnetron sputtering C23C14/3457 takes precedence
• CPC Class Codes: H01M 10/0472 Vertically superposed cells with vertically disposed plates
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0562 Solid materials
• CPC Class Codes: H01M 10/0585 of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
• CPC Class Codes: H01M 2004/028 Positive electrodes
• CPC Class Codes: H01M 2300/002 Inorganic electrolyte
• CPC Class Codes: H01M 4/0402 Methods of deposition of the material
• CPC Class Codes: H01M 4/0404 by coating on electrode collectors
• CPC Class Codes: H01M 4/0423 Physical vapour deposition
• CPC Class Codes: H01M 4/0426 Sputtering
• CPC Class Codes: H01M 4/0438 by electrochemical processing electroless electrochemical plating C23C18/54
• CPC Class Codes: H01M 4/044 Activating, forming or electrochemical attack of the supporting material
• CPC Class Codes: H01M 4/045 Electrochemical coating; Electrochemical impregnation
• CPC Class Codes: H01M 4/0471 involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
• CPC Class Codes: H01M 4/131 Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/1391 of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/485 of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy H01M4/505, H01M4/525 take precedence
• CPC Class Codes: H01M 4/525 : of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• CPC Class Codes: H01M 4/66 : Selection of materials
• CPC Class Codes: H01M 4/661 : Metal or alloys, e.g. alloy coatings H01M4/669 take precedence
• CPC Class Codes: H01M 4/667 : in the form of layers, e.g. coatings
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product

Abstract

In accordance with the present invention, deposition of LiCoO₂ 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 LiCoO₂ with a desired (101) or (003) orientation. Some embodiments of the deposition addresses the need for high rate deposition of LiCoO₂ 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 LiCoO₂ layer. Some embodiments of the process can improve a battery utilizing the LiCoO₂ layer by utilizing a rapid thermal anneal process with short ramp rates.

Claims

1. A method of depositing a LiCoO₂ 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 LiCoO₂;

positioning said target opposite said substrate;

forming a layer of LiCoO₂ over said substrate; and

applying rapid thermal annealing to said substrate and LiCoO₂ layer.

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 wherein said rapid thermal annealing process further comprises annealing said LiCoO₂ layer to a temperature of less than about 700°

C. for a period of time of less than about 10 minutes.

5. The method of claim 1, further comprising depositing a platinum layer on said substrate.

6. The method of claim 1, further comprising depositing an electrically conducting layer on the substrate.

7. The method of claim 1, further comprising applying a RF bias to said substrate while applying pulsed DC power to said sputter target.

8. The method of claim 1, wherein said LiCoO₂ layer comprises, at least in part, a crystalline structure.

9. The method of claim 1, wherein said LiCoO₂ layer comprises, at least in part, a crystalline structure and a preferred crystallographic orientation in the (101) plane.

10. The method of claim 1, wherein said LiCoO₂ layer comprises, at least in part, a crystalline structure and a preferred crystallographic orientation in the (003) plane.

11. The method of claim 1, wherein said LiCoO₂ layer comprises a grain size of between about 500 Å

and about 3000 Å

.

12. The method of claim 1, further comprising preheating said substrate to a temperature of up to about 200°

C. prior to depositing said LiCoO₂ layer.

13. The method of claim 1, further comprising preheating said substrate prior to depositing said LiCoO₂ layer;

said depositing of LiCoO₂ occurring without applying active substrate heating.

14. The method of claim 1, further comprising depositing an oxide layer on said substrate.

15. The method of claim 14, wherein said oxide layer comprises a silicon dioxide layer.

16. The method of claim 1, further comprising depositing said LiCoO₂ layer at a rate greater than about 1 μ

m per hour.

17. The method of claim 1 wherein said sputter target comprises a ceramic LiCoO₂ sputter target with a resistance measured across about 4 cm of its surface of less than about 500 kΩ

.

18. 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.

19. The method of claim 18, 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.

20. The method of claim 18, wherein said substrate comprises, at least in part, a material selected from the group of silicon, polymers, glasses, ceramics, stainless steel, and metals.

21. The method of claim 18, wherein said rapid thermal annealing process further comprises annealing said lithium metal oxide layer to a temperature of less than about 700°

C. for a period of time of less than about 10 minutes.

22. The method of claim 18, further comprising depositing a platinum layer on said substrate.

23. The method of claim 18, further comprising depositing an electrically conducting layer on the substrate.

24. The method of claim 18, further comprising applying a RF bias to said substrate while applying pulsed DC power to said sputter target.

25. The method of claim 18, wherein said lithium metal oxide layer comprises, at least in part, a crystalline structure.

26. The method of claim 18, wherein said lithium metal oxide layer comprises, at least in part, a crystalline structure and a preferred crystallographic orientation in the (101) plane.

27. The method of claim 18, wherein said lithium metal oxide layer comprises, at least in part, a crystalline structure and a preferred crystallographic orientation in the (003) plane.

28. The method of claim 18, wherein said lithium metal oxide layer comprises a grain size of between about 500 Å

and about 3000 Å

.

29. The method of claim 18, further comprising preheating said substrate to a temperature of up to about 200°

C. prior to depositing said lithium metal oxide layer.

30. The method of claim 18, 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.

31. The method of claim 18, further comprising depositing an oxide layer on said substrate.

32. The method of claim 31, wherein said oxide layer comprises a silicon dioxide layer.

33. The method of claim 18, further comprising depositing said lithium metal oxide layer at a rate greater than about 1 μ

m per hour.

34. The method of claim 18, 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

.