Fabrication of tungsten MEMS structures

US9878901B2 · kind B2 · utility

Assignee

• Analog Devices, Inc. · US

Inventors

• John A. Geen · Tewksbury, US
• George M. Molnar · Westford, US
• Gregory S. Davis · Woburn, US
• Bruce Ma · Methuen, US
• Kenneth J. Cole · Somerville, US
• James Timony · North Andover, US
• Kenneth Flanders · Reading, US

Key dates

• Filing date: Mar 27, 2015
• Grant date: Jan 30, 2018
• Expiry date: Mar 27, 2035

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04R19/005
• WIPO field: Micro-structural and nano-technology
• WIPO sector: Chemistry

Abstract

Thick (i.e., greater than two microns), fine-grained, low-stress tungsten MEMS structures are fabricated at low temperatures, particularly for so-called “MEMS last” fabrication processes (e.g., when MEMS structures are fabricated after electronic circuitry is fabricated). Means for very accurately etching structural details from the deposited tungsten layer and for strongly and stably anchoring the tungsten layer to an underlying substrate are disclosed. Also, means for removing a sacrificial layer underlying the mobile tungsten layer without damaging the tungsten or allowing it to be drawn down and stuck by surface tension is disclosed.