Depositing lithium metal oxide on a battery substrate

Abstract

A method of depositing lithium metal oxide on a battery substrate in a sputtering chamber comprising a substrate support, first and second sputtering targets each comprising lithium metal oxide, and first and second electrodes about the backside surfaces of the first and second sputtering targets respectively. In the method, a substrate is placed on the substrate support, sputtering gas maintained at a pressure and energized by applying an alternating voltage of AC power to the first and second electrodes so that each electrode is alternately either an anode or a cathode. The alternating voltage can be applied within a frequency range while also applying a time varying magnetic field about each of the surfaces of the first and second targets.

What is claimed is: 
     
         1 . A method of depositing lithium metal oxide on a battery substrate, in a sputtering chamber comprising (i) a substrate support, (ii) first and second sputtering targets each comprising a sputtering surface of lithium metal oxide and having a backside surface, and (iii) a first electrode about the backside surface of the first sputtering target and a second electrode about the backside surface of the second sputtering target, the method comprising:
 (a) placing one or more substrates on the substrate support in the sputtering chamber;   (b) maintaining a sputtering gas at a pressure in the sputtering chamber;   (c) energizing the sputtering gas by applying an alternating voltage of AC power to the first and second electrodes so that each electrode is alternately either an anode or a cathode, the alternating voltage being applied at a frequency of between about 10 and about 100 kHz; and   (d) applying a time varying magnetic field about each of the sputtering surfaces of the first and second targets.   
     
     
         2 . A method according to  claim 1  wherein the time varying magnetic field comprises a rotational frequency. 
     
     
         3 . A method according to  claim 2  wherein the rotational frequency is between about 0.005 and about 0.1 Hz. 
     
     
         4 . A method according to  claim 1  comprising providing a magnetron behind each sputtering target, the magnetron comprising first and second magnets that have different magnetic fluxes or magnetic field orientations. 
     
     
         5 . A method according to  claim 1  wherein the sputtering chamber comprises a cathode formed by binding a sputtering target to a magnetron, and wherein (d) comprises rotating the magnetron. 
     
     
         6 . A method according to  claim 5  comprising mounting a cylindrically shaped target to a cylindrically shaped magnetron. 
     
     
         7 . A method according to  claim 1  wherein the sputtering chamber comprises a cathode formed by binding a sputtering target to a magnetron comprising a rotatable magnet assembly, and wherein (d) comprises rotating the magnet assembly. 
     
     
         8 . A method according to  claim 1  comprising applying the alternating voltage at at least one of (i) a frequency of from about 20 to about 80 kHz, and (ii) a power level of from about 3 kW to about 10 kW. 
     
     
         9 . A method according to  claim 1  wherein the substrate support is electrically isolated from a sputtering chamber wall and from the first and second sputtering targets and wherein (a) comprises applying to the substrate support, a biasing voltage that is at least one of (i) a pulsed voltage, (ii) from about −20V to about −200V, and (iii) has a duty cycle from 10% to 90%. 
     
     
         10 . A method according to  claim 1  wherein the lithium metal oxide comprises lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium iron oxide, lithium cobalt nickel oxide, or a mixtures of transition metals. 
     
     
         11 . A method according to  claim 1  wherein the lithium metal oxide consists essentially of lithium cobalt oxide. 
     
     
         12 . A method of depositing lithium cobalt oxide on a battery substrate in a sputtering chamber comprising (i) a substrate support, (ii) first and second sputtering targets each comprising a sputtering surface of lithium cobalt oxide and having a backside surface, and (iii) a first electrode about the backside surface of the first sputtering target and a second electrode about the backside surface of the second sputtering target, the method comprising:
 (a) placing one or more substrates on the substrate support in the sputtering chamber;   (b) maintaining a sputtering gas at a pressure in the sputtering chamber;   (c) energizing the sputtering gas by applying an alternating voltage of AC power to the first and second electrodes so that each electrode is alternately either an anode or a cathode, the alternating voltage being applied at a frequency of between about 10 and about 100 kHz; and   (d) applying a time varying magnetic field about each of the sputtering surfaces of the first and second targets, the time varying magnetic field comprising a rotational frequency of between about 0.005 and about 0.1 Hz.   
     
     
         13 . A method according to  claim 12  comprising providing a magnetron behind each sputtering target, the magnetron comprising first and second magnets that have different magnetic fluxes or magnetic field orientations. 
     
     
         14 . A method according to  claim 12  wherein the sputtering chamber comprises a cathode formed by binding a sputtering target to a magnetron, and wherein (d) comprises rotating the magnetron. 
     
     
         15 . A method according to  claim 12  wherein the sputtering chamber comprises a cathode formed by binding a sputtering target to a magnetron comprising a rotatable magnet assembly, and wherein (d) comprises rotating the magnet assembly. 
     
     
         16 . A method according to  claim 12  comprising applying the alternating voltage at at least one of a frequency of from about 20 to about 80 kHz and a power level of from about 3 kW to about 10 kW. 
     
     
         17 . A method of depositing lithium cobalt oxide on a battery substrate in a sputtering chamber comprising (i) a substrate support, (ii) first and second sputtering targets that each have a sputtering surface consisting essentially of lithium cobalt oxide, and (iii) a first electrode about the first sputtering target and a second electrode about the second sputtering target, the method comprising:
 (a) placing one or more substrates on the substrate support in the sputtering chamber;   (b) maintaining a sputtering gas at a pressure in the sputtering chamber;   (c) energizing the sputtering gas by applying an alternating voltage of AC power to the first and second electrodes so that each electrode is alternately either an anode or a cathode, the alternating voltage being applied at a frequency of between about 10 and about 100 kHz;   (d) providing a magnetron about each of the first and second sputtering targets, each magnetron comprising a first magnet having a first magnetic flux or first magnetic field orientation, and one or more peripheral magnets having a second magnetic flux or second magnetic field orientation; and   (e) applying a time varying magnetic field about each of the sputtering surfaces of the first and second targets, the time varying magnetic field comprising a rotational frequency of between about 0.005 and about 0.1 Hz.