Microelectronic mechanical system and methods
First Claim
1. A method of making a release structure from a multi-layer structure comprising first and second etch-stop layers, a first sacrificial layer between the first and the second etch-stop layers, a cap layer and a second sacrificial layer between the second etch-stop layer and the cap layer with at least one access trench, wherein the second etch-stop layer includes a release feature, the method comprising;
- a. creating an access opening in the cap layer; and
b. etching portions of the first and the second sacrificial layers through the at least one access opening to form the release structure.
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Abstract
The current invention provides for encapsulated release structures, intermediates thereof and methods for their fabrication. The multi-layer structure has a capping layer, that preferably comprises silicon oxide and/or silicon nitride, and which is formed over an etch resistant substrate. A patterned device layer, preferably comprising silicon nitride, is embedded in a sacrificial material, preferably comprising polysilicon, and is disposed between the etch resistant substrate and the capping layer. Access trenches or holes are formed in to capping layer and the sacrificial material are selectively etched through the access trenches, such that portions of the device layer are release from sacrificial material. The etchant preferably comprises a noble gas fluoride NGF2x (wherein Ng=Xe, Kr or Ar: and where x=1, 2 or 3). After etching that sacrificial material, the access trenches are sealed to encapsulate released portions the device layer between the etch resistant substrate and the capping layer. The current invention is particularly useful for fabricating MEMS devices, multiple cavity devices and devices with multiple release features.
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Citations
58 Claims
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1. A method of making a release structure from a multi-layer structure comprising first and second etch-stop layers, a first sacrificial layer between the first and the second etch-stop layers, a cap layer and a second sacrificial layer between the second etch-stop layer and the cap layer with at least one access trench, wherein the second etch-stop layer includes a release feature, the method comprising;
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a. creating an access opening in the cap layer; and
b. etching portions of the first and the second sacrificial layers through the at least one access opening to form the release structure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of making a MEMS device comprising:
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a forming a first sacrificial layer on a substrate;
c. forming a MEM feature comprising an etch resistant material over the first sacrificial layer, the MEM structure layer having at least one gap therein;
d. forming a second sacrificial layer on the MEM structure layer; and
e. forming a capping layer over the second sacrificial layer. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A structure for fabricating a MEMS comprising:
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a. a substrate;
b. a capping layer over a portion of the substrate; and
c. a release structure with release features, the release features being positioned between the wafer structure and embedded with a sacrificial material. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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- 37. A structure for forming a plurality of interconnected cavities, comprising a multi-layer structure comprising at least a first etch-stop layer, a second etch-stop layer, a capping layer, and polysilicon between the first and second etch-stop layers and between the second etch stop layer and the capping layer, the structure further comprising at least one internal passage in the second etch-stop layer for forming the plurality of interconnected cavities.
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42. A MEMS comprising:
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a. a wafer structure;
b. a capping layer formed on the wafer structure; and
c. a release structure comprising a plurality of movable release features encapsulated between the wafer structure and the capping layer. - View Dependent Claims (43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58)
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Specification