Micromachined assembly with a multi-layer cap defining a cavity
First Claim
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1. A method of creating a sealed cavity on a wafer comprising the steps of:
- depositing one or more layers of a sacrificial material on said wafer and shaping said sacrificial material;
depositing a first cap layer on said one or more layers of sacrificial material;
removing said one or more layers of sacrificial material such that said first cap layer and the portion of said wafer underlying said first cap layer define said cavity; and
depositing one or more additional cap layers on said first cap layer, said one or more additional cap layers being formed of a high stiffness material;
wherein said one or more cap layers contact said wafer.
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Abstract
This invention comprises a process for fabricating a micro mechanical structure in a sealed cavity having a multi-layer high stiffness cap. The high stiffness material used for the cap protects the underlying microstructure from destructive environmental forces inherent in the packaging process and from environmental damage.
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Citations
134 Claims
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1. A method of creating a sealed cavity on a wafer comprising the steps of:
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depositing one or more layers of a sacrificial material on said wafer and shaping said sacrificial material;
depositing a first cap layer on said one or more layers of sacrificial material;
removing said one or more layers of sacrificial material such that said first cap layer and the portion of said wafer underlying said first cap layer define said cavity; and
depositing one or more additional cap layers on said first cap layer, said one or more additional cap layers being formed of a high stiffness material;
wherein said one or more cap layers contact said wafer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A micro-sealed cavity comprising:
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a wafer;
a cap structure covering at least a portion of said wafer, said cap structure contacting said wafer to define a cavity thereunder;
wherein said cap structure is composed of a high stiffness material. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. In a wafer for containing a microstructure, an improvement comprising:
depositing one or more layers of high stiffness material over said microstructure to define a sealed cavity between said wafer and said one or more layers of high stiffness material. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 69)
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68. A method of fabricating an encapsulated micromachined assembly, comprising the steps of:
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providing a substrate;
depositing a first layer of sacrificial material on said substrate;
forming a microstructure of a desired shape on said first layer of sacrificial material;
depositing a second layer of sacrificial material on said first layer of sacrificial material, said second layer covering said microstructure;
depositing a first cap layer on top of said first and said second layers of sacrificial material;
removing said first and said second layers of sacrificial materials; and
depositing one or more additional cap layers on top of said first cap layer, said one or more additional cap layers being formed of a high stiffness material. - View Dependent Claims (70, 71, 72, 73)
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74. A MEMS device comprising:
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a substrate;
a microstructure formed on said substrate;
a cap covering said microstructure; and
one or more additional layers of high stiffness material covering said cap. - View Dependent Claims (75, 76, 77, 78, 79, 80, 81)
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82. A micromachined assembly comprising:
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a substrate having a support surface on one side;
a cap layer extending from points on said support surface disposed about a region of interest on said support surface and including a portion overlying said region of interest;
a cap overlayer extending from said support surface and disposed over and contiguous with said cap layer;
whereby said cap layer and said cap overlayer and said support surface define a closed capsule about an interior region containing said region of interest; and
wherein at least one of said cap layer and said cap overlayer is formed of a high stiffness material. - View Dependent Claims (83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109)
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110. A micromachined assembly, comprising:
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a substrate having a support surface on one side and a base surface on a side opposite said support surface;
a microstructure disposed on said support surface;
a sputter-deposited cap layer extending from points on said support surface and disposed over at least a portion of said microstructure, said cap layer and said device support surface defining a capsule about an interior region containing said microstructure, said cap layer being formed of a material characterized by a high stiffness. - View Dependent Claims (111, 112, 113, 114)
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115. A microstructure comprising:
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a wafer, a cap, said cap contacting said wafer around a closed perimeter to define a cavity between said wafer and said cap;
wherein said cap is composed of a plurality of layers. - View Dependent Claims (116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128)
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129. A method of creating a sealed micro cavity on a wafer comprising the steps of:
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depositing one or more layers of a sacrificial material on said wafer;
depositing a plurality of cap layers over said sacrificial material, individual ones of said plurality of cap layers being defined by a change in one or more deposition parameters or a change in material between one layer and the next. - View Dependent Claims (130, 131, 132, 133, 134)
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Specification