Sputtering of lithium
AssigneeMinnesota Mining and Manufacturing Company
InventorStephen C. Schulz
Life of this patent
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Abstract
Lithium is sputtered from a target with a metallic lithium surface using an alternating sputtering potential with a frequency between about 8 and about 120 kHz, preferably about 10-100 kHz or using a DC sputtering potential and a reverse cleaning potential applied intermittently. The process can be used to apply lithium to electrochromic materials such as coatings on window glass.
Claims38
A method of sputtering lithium comprising the steps of:
- (a) providing a target including a top layer of metallic lithium defining an exposed surface and a metallic supporting layer, a counterelectrode and a substrate;
- (b) maintaining the target, counterelectrode and substrate in a substantially inert atmosphere at subatmospheric pressure;
- and, while maintaining the target in said substantially inert atmosphere:
- (c) applying a sputtering potential between said counterelectrode and said target, said sputtering potential including being either an alternating potential or a direct potential in a forward direction so that said target is negative with respect to said counterelectrode, said step of applying a sputtering potential being performed so as to maintain a plasma adjacent to said target and sputter metallic lithium from said target under the influence of said sputtering potential;
- and
- (d) during one or more intervals prior to termination of said first potential, applying a clearing potential between said counterelectrode and said target, said clearing potential being different from said sputtering potential and including a reverse potential in a reverse direction opposite to said forward direction.
A method of sputtering lithium comprising the steps of:
- (a) providing a target including a top layer of metallic lithium defining an exposed surface and a metallic supporting layer, a counterelectrode and a substrate;
- (b) maintaining the target, counterelectrode and substrate in a substantially inert atmosphere at subatmospheric pressure;
- and, while maintaining the target in said substantially inert atmosphere:
- (c) applying a sputtering potential between said counterelectrode and said target, said sputtering potential including being either an alternating potential or a direct potential in a forward direction so that said target is negative with respect to said counterelectrode, said step of applying a sputtering potential being performed so as to maintain a plasma adjacent to said target and sputter metallic lithium from said target under the influence of said sputtering potential;
- and
- (d) cleaning said exposed surface by applying a clearing potential between said counterelectrode and said target during a first interval before application of said sputtering potential, said clearing potential being different from said sputtering potential and including a reverse potential in a reverse direction opposite to said forward direction.
A method of sputtering lithium comprising the steps of maintaining a first target including a top layer of metallic lithium defining an exposed surface and a metallic supporting layer, said top layer being metallurgically bonded to said supporting layer, a counterelectrode and a substrate in a substantially inert gas at subatmospheric pressure and imposing a potential between said target and said counterelectrode so as to form a plasma adjacent to said target and bombard said exposed surface with ions of said gas to thereby expel lithium from said target to said substrate, said step of imposing said potential including the step of applying an alternating potential having a reversing frequency between about 8 kHz and about 120 kHz.
A method of sputtering lithium comprising the steps of:
- (a) providing a target including a top layer of metallic lithium defining an exposed surface and a metallic supporting layer, a counterelectrode and a substrate;
- (b) maintaining the target, counterelectrode and substrate in a substantially inert atmosphere at subatmospheric pressure;
- and, while maintaining the target in said substantially inert atmosphere:
- (c) applying a sputtering potential between said counterelectrode and said target, said sputtering potential including being either an alternating potential or a direct potential in a forward direction so that said target is negative with respect to said counterelectrode, said step of applying a sputtering potential being performed so as to maintain a plasma adjacent to said target and sputter metallic lithium from said target under the influence of said sputtering potential;
- and
- (d) during one or more intervals prior to termination of said first potential, applying a clearing potential between said counterelectrode and said target, said clearing potential being different from said sputtering potential and including a reverse potential in a reverse direction opposite to said forward direction,
- the method further comprising the step of continuously moving said substrate in a direction of motion during said step of imposing a potential to thereby expose new regions of the substrate to said expelled lithium.
A method of sputtering lithium comprising the steps of:
- (a) providing a target including a top layer of metallic lithium defining an exposed surface and a metallic supporting layer, a counterelectrode and a substrate;
- (b) maintaining the target, counterelectrode and substrate in a substantially inert atmosphere at subatmospheric pressure;
- and, while maintaining the target in said substantially inert atmosphere:
- (c) applying a sputtering potential between said counterelectrode and said target, said sputtering potential including being either an alternating potential or a direct potential in a forward direction so that said target is negative with respect to said counterelectrode, said step of applying a sputtering potential being performed so as to maintain a plasma adjacent to said target and sputter metallic lithium from said target under the influence of said sputtering potential;
- and
- (d) cleaning said exposed surface by applying a clearing potential between said counterelectrode and said target during a first interval before application of said sputtering potential, said clearing potential being different from said sputtering potential and including a reverse potential in a reverse direction opposite to said forward direction,
- the method further comprising the step of continuously moving said substrate in a direction of motion during said step of imposing a potential to thereby expose new regions of the substrate to said expelled lithium.
A method of sputtering lithium comprising the steps of maintaining a first target including a top layer of metallic lithium defining an exposed surface and a metallic supporting layer, said top layer being metallurgically bonded to said supporting layer, a counterelectrode and a substrate in a substantially inert gas at subatmospheric pressure and imposing a potential between said target and said counterelectrode so as to form a plasma adjacent to said target and bombard said exposed surface with ions of said gas to thereby expel lithium from said target to said substrate, said step of imposing said potential including the step of applying an alternating potential having a reversing frequency between about 8 kHz and about 120 kHz,
- the method further comprising the step of continuously moving said substrate in a direction of motion during said step of imposing a potential to thereby expose new regions of the substrate to said expelled lithium.
Dependencies are inferred from the claim text.