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Title: Tungsten coating for improved wear resistance and reliability of microelectromechanical devices

Patent ·
OSTI ID:873999
 [1];  [1];  [2];  [1]
  1. Albuquerque, NM
  2. Edgewood, NM
+ Show Author Affiliations

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, electrical conductivity, optical reflectivity and chemical inertness of one or more semiconductor surfaces within a MEM device.

Research Organization:
Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
DOE Contract Number:
AC04-94AL85000
Assignee:
Sandia Corporation (Albuquerque, NM)
Patent Number(s):
US 6290859
OSTI ID:
873999
Country of Publication:
United States
Language:
English

References (10)

Selective Low Pressure Chemical Vapor Deposition of Tungsten journal January 1984
Selective CVD tungsten as an alternative to blanket tungsten for submicron plug applications on VLSI circuits conference January 1991
Studies of the Possible Reaction of  WF 6 with SiO2 and Si3 N 4 at Several Temperatures journal August 1992
Effect of surface pretreatment of submicron contact hole on selective tungsten chemical vapor deposition journal January 1996
Structure of Selective Low Pressure Chemically Vapor‐Deposited Films of Tungsten journal May 1985
Transport Phenomena in Tungsten LPCVD in a Single‐Wafer Reactor journal February 1991
Deposition properties of selective tungsten chemical vapor deposition journal September 1996
Interface reactions between CVD and PVD tungsten and aluminium journal November 1993
Evaluation of the Selective Tungsten Deposition Process for VLSI Circuit Applications journal April 1988
Influence of surface‐activated reaction kinetics on low‐pressure chemical vapor deposition conformality over micro features journal January 1993

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Related Subjects

tungsten
coating
improved
wear
resistance
reliability
microelectromechanical
devices
process
disclosed
whereby
5-50-nanometer-thick
conformal
formed
exposed
semiconductor
surfaces
silicon
germanium
carbide
device
cleaning
remove
organic
material
oxide
film
surface
final
situ
step
performed
heating
substrate
containing
temperature
range
200-600
degree
presence
gaseous
nitrogen
trifluoride
nf
chemical
reaction
hexafluoride
wf
elevated
preferably
450
deposition
self-limiting
covers
including
close
contact
applied
types
microrelays
micromirrors
microengines
additionally
wear-resistant
enhance
hardness
electrical
conductivity
optical
reflectivity
inertness
resistant coating
microelectromechanical devices
tungsten coating
elevated temperature
silicon carbide
chemical reaction
electrical conductivity
deposition process
semiconductor surface
oxide film
organic material
semiconductor surfaces
gaseous nitrogen
wear resistance
devices including
mechanical device
optical reflectivity
close contact
substrate containing
improved wear
chemical inertness
tungsten hexafluoride
electromechanical devices
mechanical devices
microelectromechanical device
wear-resistant coating
substrate contain
situ cleaning
/216/134/427/428/438/