Method of undercutting micro-mechanical device with super-critical carbon dioxide
First Claim
1. An improved method of fabricating a micro-mechanical device, the method comprising:
- depositing at least one sacrificial layer on a substrate;
curing the sacrificial layer;
fabricating a micro-mechanical device on the sacrificial layer;
removing the sacrificial layer by immersing the substrate in a cleansing solution comprising super-critical carbon dioxide and a solvent suitable to remove the sacrificial layer.
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Abstract
A method for removing sacrificial layers during the process of fabricating micro-mechanical devices with a solution of super-critical carbon dioxide. A mixture of super-critical carbon dioxide with other solvents, co-solvents and surfactants is used during the process to remove sacrificial layers. The disclosed method has many advantages over the prior art, including a reduction of capillary forces that can damage the free-standing micro-mechanical superstructures, an absence of plasma induced damage caused by ashing operations, and a reduction in the use of environmentally sensitive chemicals. Another advantage of the disclosed process is that the swelling of the photoresist layers is minimized. The disclosed method may be used to remove sacrificial layers that were deposited during the process of fabricating micro-mechanical devices. The method is also effective to remove a protective recoat layer that is deposited over a micro-mechanical device after it has been fabricated.
22 Citations
37 Claims
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1. An improved method of fabricating a micro-mechanical device, the method comprising:
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depositing at least one sacrificial layer on a substrate;
curing the sacrificial layer;
fabricating a micro-mechanical device on the sacrificial layer;
removing the sacrificial layer by immersing the substrate in a cleansing solution comprising super-critical carbon dioxide and a solvent suitable to remove the sacrificial layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An improved method of fabricating a micro-mechanical device, the method comprising:
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depositing at least one sacrificial layer on a substrate;
curing the sacrificial layer;
fabricating a micro-mechanical device on the first sacrificial layer;
removing the first sacrificial layer;
recoating the micro-mechanical device with a recoat layer of sufficient thickness to completely encapsulate the micro-mechanical device;
curing the recoat layer;
removing the recoat layer by immersing the substrate in a cleansing solution comprising super-critical carbon dioxide and a solvent suitable to remove the sacrificial layer. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An improved method of fabricating a micro-mechanical device, the method comprising:
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depositing a first sacrificial layer on a substrate;
removing portions of the first sacrificial layer to define a first set of vias;
depositing a first metal layer on the first sacrificial layer;
removing portions of the first metal layer to define a set of first via supports;
depositing a second sacrificial layer on the first metal layer;
removing portions of the second sacrificial layer to define a second set of vias;
depositing a second metal layer on the second sacrificial layer;
removing portions of the second metal layer to define a set of second vias;
removing the first and second sacrificial layers by immersing the substrate in a cleansing solution comprising super-critical carbon dioxide and a solvent suitable to remove the sacrificial layers. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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28. An improved method of fabricating a micro-mechanical device, the method comprising:
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depositing a first sacrificial layer on a substrate;
removing portions of the first sacrificial layer to define a first set of vias;
depositing a first metal layer on the first sacrificial layer;
removing portions of the first metal layer to define a set of first via supports;
depositing a second sacrificial layer on the first metal layer;
removing portions of the second sacrificial layer to define a set of second via forms;
depositing a second metal layer on the second sacrificial layer;
removing portions of the second metal layer to define a set of second via supports;
recoating the micro-mechanical device with a recoat layer of sufficient thickness to completely encapsulate the micro-mechanical device;
curing the recoat layer;
removing the recoat layer by immersing the substrate in a cleansing solution comprising super-critical carbon dioxide and a solvent suitable to remove the recoat layer. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification