US 5,963,788 A · Method for integrating microelectromechanical devices with electronic circuitry

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.

Claims43

Dependent claims

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.

3 more elements

Dependencies are inferred from the claim text.

Method for integrating microelectromechanical devices with electronic circuitry

Life of this patent

Method for integrating microelectromechanical devices with electronic circuitry

Life of this patent

Abstract

Claims43