Method for integrating microelectromechanical devices with electronic circuitry
First Claim
1. A method for integrating a microelectromechanical (MEM) device with electronic circuitry on a substrate comprising steps for:
- (a) etching a cavity within a first portion of the substrate;
(b) fabricating the MEM device within the cavity, and filling the cavity with a sacrificial material;
(c) fabricating the electronic circuitry comprising a plurality of transistors within a second portion of the substrate proximate to the first portion, and interconnecting the electronic circuitry to the MEM device;
(d) protecting the electronic circuitry by depositing a layer of tungsten to blanket the second portion of the substrate and cover the electronic circuitry; and
(e) releasing the MEM device for operation thereof by removing at least a portion of the sacrificial material filling the cavity by etching the sacrificial material with a first wet etchant which does not substantially remove the layer of tungsten protecting the electronic circuitry.
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Accused Products
Abstract
A method is disclosed for integrating one or more microelectromechanical (MEM) devices with electronic circuitry on a common substrate. The MEM device can be fabricated within a substrate cavity and encapsulated with a sacrificial material. This allows the MEM device to be annealed and the substrate planarized prior to forming electronic circuitry on the substrate using a series of standard processing steps. After fabrication of the electronic circuitry, the electronic circuitry can be protected by a two-ply protection layer of titanium nitride (TiN) and tungsten (W) during an etch release process whereby the MEM device is released for operation by etching away a portion of a sacrificial material (e.g. silicon dioxide or a silicate glass) that encapsulates the MEM device. The etch release process is preferably performed using a mixture of hydrofluoric acid (HF) and hydrochloric acid (HCI) which reduces the time for releasing the MEM device compared to use of a buffered oxide etchant. After release of the MEM device, the TiN:W protection layer can be removed with a peroxide-based etchant without damaging the electronic circuitry.
301 Citations
43 Claims
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1. A method for integrating a microelectromechanical (MEM) device with electronic circuitry on a substrate comprising steps for:
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(a) etching a cavity within a first portion of the substrate; (b) fabricating the MEM device within the cavity, and filling the cavity with a sacrificial material; (c) fabricating the electronic circuitry comprising a plurality of transistors within a second portion of the substrate proximate to the first portion, and interconnecting the electronic circuitry to the MEM device; (d) protecting the electronic circuitry by depositing a layer of tungsten to blanket the second portion of the substrate and cover the electronic circuitry; and (e) releasing the MEM device for operation thereof by removing at least a portion of the sacrificial material filling the cavity by etching the sacrificial material with a first wet etchant which does not substantially remove the layer of tungsten protecting the electronic circuitry. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for integrating a microelectromechanical (MEM) device with electronic circuitry on a substrate comprising steps for:
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(a) fabricating the MEM device at least in part within or from a cavity formed in a first portion of the substrate and encapsulating the MEM device with a sacrificial material; (b) fabricating the electronic circuitry in a second portion of the substrate, and interconnecting the electronic circuitry to the MEM device; (c) depositing layers of titanium nitride and tungsten over the electronic circuitry for protecting the electronic circuitry from exposure to a first wet etchant comprising, at least in part, hydrofluoric acid; and (d) releasing the MEM device for operation by etching away at least a portion of the sacrificial material encapsulating the MEM device with the first wet etchant. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A method for integrating a microelectromechanical (MEM) device with electronic circuitry on a substrate comprising steps for:
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(a) fabricating the MEM device at least in part within or from a cavity formed in a first portion of the substrate and encapsulating the MEM device with a sacrificial material; (b) planarizing the substrate to remove any of the sacrificial material extending upward beyond the cavity thereby providing a substantially planar upper surface for the substrate; (c) fabricating the electronic circuitry in a second portion of the substrate, and interconnecting the electronic circuitry to the MEM device; (d) protecting the electronic circuitry by depositing layers of titanium nitride and tungsten over the electronic circuitry in the second portion of the substrate; (e) releasing the MEM device by exposing the MEM device to a first wet etching comprising, at least in part, hydrofluoric acid for sufficient time to remove a portion of the sacrificial material encapsulating the MEM device; and (f) removing the deposited layers of titanium nitride and tungsten protecting the electronic circuitry. - View Dependent Claims (37, 38, 39, 40, 41, 42, 43)
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Specification