SPUTTERING LITHIUM-CONTAINING MATERIAL WITH MULTIPLE TARGETS

• US 20130164459A1
• Filed: 12/23/2011
• Published: 06/27/2013
• Est. Priority Date: 12/23/2011
• Status: Active Grant

• Current Assignee: KLA Corporation
• Original Assignee: Front Edge Technology, Inc
• Inventors: NIEH, Kai Wei, Krasnov, Victor, Liang, Jiuh-Ming
• Granted Patent: US 8,864,954 B2
• Time in Patent Office: Days
• US Class Current: 427/580
• CPC Class Codes: C23C 14/08 Oxides C23C14/10 takes precedence
• CPC Class Codes: C23C 14/352 using more than one target C23C14/56 takes precedence
• CPC Class Codes: C23C 14/505 for rotation of the substrates
• CPC Class Codes: H01J 37/3426 Material
• CPC Class Codes: H01M 4/0426 Sputtering
• 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: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A method of depositing lithium-containing films on a battery substrate in a sputtering chamber is provided. At least one pair of sputtering targets that each comprise a lithium-containing sputtering member is provided in the sputtering chamber, the sputtering targets selected to each have a conductivity of at least about 5×10⁻⁶ S·cm⁻¹. A substrate carrier holding at least one battery substrate is placed in the sputtering chamber. A pressure of sputtering gas is maintained in the sputtering chamber. The sputtering gas is energized by applying to the pair of sputtering targets, an electrical power at a frequency of from about 10 to about 100 kHz.

Claims

1. A method of depositing lithium-containing films on a battery substrate in a sputtering chamber, the method comprising:

(a) providing in the sputtering chamber, at least one pair of sputtering targets that each comprise a lithium-containing sputtering member, the sputtering targets selected to each have a conductivity of at least about 5×

10<sup>−

6</sup> S·

cm<sup>−

1</sup>;

(b) placing in the sputtering chamber, a substrate carrier holding at least one battery substrate;

(c) maintaining a pressure of a sputtering gas in the sputtering chamber; and

(d) energizing the sputtering gas by applying to the pair of sputtering targets, an electrical power at a frequency of from about 10 to about 100 kHz.

2. A method according to claim 1 wherein each sputtering target comprises a backing plate having a back surface, and each lithium-containing sputtering member has a front surface, and wherein (a) comprises measuring an electrical conductivity at multiple points across each sputtering target by applying a two probe test across the front and back surfaces of the sputtering target.

3. A method according to claim 1 wherein (a) comprises selecting sputtering targets having an average conductivity of at least about 5×

10<sup>−

6</sup> S·

cm<sup>−

1</sup>.

4. A method according to claim 2 comprising selecting a pair of sputtering targets such that the average electrical conductivity of each of the two sputtering targets varies by less than about 10%.

5. A method according to claim 1 wherein (b) comprises applying to the substrate carrier, a negative pulsed DC bias voltage comprising at least one of the following:

(i) a voltage level of from about −

5 V to about −

200 V; and

(ii) a duty cycle from about 10% to about 90%.

6. A method according to claim 1 wherein the sputtering gas comprises at least one of argon or oxygen.

7. A method according to claim 1 wherein the lithium-containing sputtering member comprises lithium metal oxide.

8. A method according to claim 7 wherein the lithium metal oxide comprises lithium cobalt oxide.

9. A method according to claim 1 further comprising before (a) or after (d), depositing a plurality of battery component films that cooperate to form a battery, the battery component films comprising at least a pair of electrodes and an electrolyte, and wherein the deposited lithium-containing film serves as an electrode.

10. A method according to claim 1 comprising during (d), adjusting the impedance of one of the pair of sputtering targets to be within a range that is ±

10% of the impedance of the other sputtering target.

11. A method of depositing lithium-containing films on a battery substrate in a sputtering chamber, the method comprising:

(a) providing in the sputtering chamber, first and second sputtering targets that each comprise a lithium-containing sputtering member;

(b) placing in the sputtering chamber, a substrate carrier holding at least one battery substrate;

(c) maintaining a pressure of a sputtering gas in the sputtering chamber;

(d) adjusting the impedance of the first sputtering target to be within a range that is ±

10% of the impedance of the second sputtering target; and

(e) energizing the sputtering gas by applying to the first and second sputtering targets, an electrical power at a frequency of from about 10 to about 100 kHz.

12. A method according to claim 11 wherein (d) comprises adjusting the impedance of the first sputtering target to be within a range that is ±

5% of impedance of the second sputtering target.

13. A method according to claim 11 wherein (d) comprises measuring the voltage and current of the electrical power applied to the first and second sputtering targets, and adjusting the impedance of at least one of the first and second sputtering target in relation to the measured voltage and current.

14. A method according to claim 11 wherein (d) comprises adjusting the impedance of at least one of the pair of sputtering targets so that the power supply applies a first power level to the first sputtering target and a second power level to the second sputtering target, the first and second power levels being selected in relation to the measured voltage and current.

15. A method according to claim 11 wherein (a) comprises providing first and second sputtering targets that each have an average electrical conductivity of at least about 5×

10<sup>−

6</sup> S·

cm<sup>−

1</sup>.

16. A sputtering apparatus for depositing lithium-containing films on a battery substrate, the apparatus comprising:

(a) a sputtering chamber comprising;

(i) at least one pair of sputtering targets mounted in the chamber, each sputtering target comprising a lithium-containing sputtering member and a backing plate;

(ii) a substrate carrier holding at least one battery substrate;

(iii) a gas distributor for introducing a sputtering gas into the sputtering chamber; and

(iv) an exhaust for maintaining a pressure of the sputtering gas in the sputtering chamber; and

(b) a target power source comprising;

(i) an impedance matching circuit for adjusting the impedance of at least one of the pair of sputtering targets so that the impedance of that sputtering target is within a range that is +10% of the impedance of the other sputtering target; and

(ii) at least one power supply to apply to the pair of sputtering targets, an electrical power at a frequency of from about 10 to about 100 kHz.

17. An apparatus according to claim 16 wherein the impedance matching circuit adjusts the impedance of at least one of the pair of sputtering targets so that the impedance of that sputtering target is within a range that is +5% of the impedance of the other sputtering target.

18. An apparatus according to claim 16 wherein the impedance matching circuit measures the voltage and current of the electrical power applied to the sputtering targets, and matches the impedance of the sputtering targets by adjusting a variable resistor or variable transformer.

19. An apparatus according to claim 16 wherein the impedance matching circuit adjust the impedance of at least one of the pair of the sputtering targets so that the power supply applies a first power level to one of the targets and a second power level to the other target, the first and second power levels being selected in relation to the measured voltage and current.

20. A kit of a plurality of sputtering targets, wherein each sputtering target comprises:

(a) a conductivity of at least about 5×

10<sup>−

6</sup> S·

cm<sup>−

1</sup>;

(b) a backing plate having a back surface; and

(c) a lithium-containing sputtering member having a front surface.

21. A method according to claim 20 wherein the lithium-containing sputtering member comprises a lithium metal oxide.