Browse Prior Art Database

Pump/ Purge Procedure using Neon Feedstock

IP.com Disclosure Number: IPCOM000108044D
Original Publication Date: 1992-Apr-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Selwyn, GS: AUTHOR

Abstract

Disclosed is a method for improved pump/purge removal of particle contamination in vacuum process tools using neon feedstock purge gas. This method is also effective in aiding removal of electrostatically trapped particles in plasma processing tools.

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This is the abbreviated version, containing approximately 52% of the total text.

Pump/ Purge Procedure using Neon Feedstock

       Disclosed is a method for improved pump/purge removal of
particle contamination in vacuum process tools using neon feedstock
purge gas.  This method is also effective in aiding removal of
electrostatically trapped particles in plasma processing tools.

      Particles present in a plasma, such as those used in
microelectronics fabrication, are suspended near the plasma/sheath
boundary (1-3).  The particles are also electrostatically attracted
to three- dimensional particle traps caused by topographic or
material discontinuities on the electrode (4-5).  Feed gas drag force
(6) can exceed the electrostatic attraction and flush the particles
out of the plasma into the pump port.  To increase the drag force the
use of Ne is disclosed because of its anomalously high gas viscosity
coefficient (7).

      The use of Ne to increase gas drag force also has beneficial
properties for pump/purge procedures used on all vacuum tools.  In
this procedure, a vacuum chamber is first backfilled with a pressure
of Ne and then is evacuated. Often, the procedure is repeated several
times to help remove suspended, submicron particles.  The rate of
particle settling is given by equating drag force with gravitational
forces (6).  The drag force is,

                            (Image Omitted)

where h is the gas viscosity, v is the gas  velocity, d is the
particle diameter, and C is the Cunningham slip factor (6).  The
gravitational force is
where p is the particle density and g is  the...