Tungsten coating for improved wear resistance and reliability of microelectromechanical devices
US6290859A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 12, 1999 |
| Grant date | Sep 18, 2001 |
| Priority date | — |
| Expiry date | Nov 12, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01H2001/0057
- WIPO fieldMicro-structural and nano-technology
- WIPO sectorChemistry
Abstract
A process is disclosed whereby a 5-50-nanometer-thick conformal tungsten coating can be formed over exposed semiconductor surfaces (e.g. silicon, germanium or silicon carbide) within a microelectromechanical (MEM) device for improved wear resistance and reliability. The tungsten coating is formed after cleaning the semiconductor surfaces to remove any organic material and oxide film from the surface. A final in situ cleaning step is performed by heating a substrate containing the MEM device to a temperature in the range of 200-600 .degree. C. in the presence of gaseous nitrogen trifluoride (NF.sub.3). The tungsten coating can then be formed by a chemical reaction between the semiconductor surfaces and tungsten hexafluoride (WF.sub.6) at an elevated temperature, preferably about 450.degree. C. The tungsten deposition process is self-limiting and covers all exposed semiconductor surfaces including surfaces in close contact. The present invention can be applied to many different types of MEM devices including microrelays, micromirrors and microengines. Additionally, the tungsten wear-resistant coating of the present invention can be used to enhance the hardness, wear resistance, elect…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.