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Electrical Measurement of Sputter Deposition Rate of Trenches

IP.com Disclosure Number: IPCOM000110137D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 3 page(s) / 108K

Publishing Venue

IBM

Related People

Gut, GM: AUTHOR [+2]

Abstract

A method for electrically measuring sputter deposition rates into long narrow serpentine trenches is disclosed. This method is used for evaluating the trench deposition efficiency for different sputter process conditions. The unique feature of this scheme is the ability to accurately determine the conductor thickness in the bottom of a trench without the use of expensive analytical equipment.

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Electrical Measurement of Sputter Deposition Rate of Trenches

       A method for electrically measuring sputter deposition
rates into long narrow serpentine trenches is disclosed.  This method
is used for evaluating the trench deposition efficiency for different
sputter process conditions.  The unique feature of this scheme is the
ability to accurately determine the conductor thickness in the bottom
of a trench without the use of expensive analytical equipment.

      Sputter deposition of conductors is a key technology of
integrated circuit processing.  Sputter deposition consists of using
a glow discharge as a source of positively charged ions and
accelerating these ions through the cathode sheath to the cathode
(also known as the target).  When these ions strike the target, atoms
of target material are ejected.  These atoms diffuse through the
plasma to a substrate located at the anode.  The angle at which these
atoms impinge the substrate is unknown.  The rate at which the film
grows in the trenches is slower than film growth on a flat substrate.
This growth reduction is due to the trench sidewalls shadowing the
trench bottom from some of the incident flux of target atoms.

      There are many interactions such as collisions and plasma
electric field which affect the motion of the atoms.  Modeling
particle motion would be difficult and would yield questionable
results.  An experimental method for determining the trench
deposition rate is needed.  Here, a scheme for building and testing
substrates of desired trench dimensions is described.

      The first step of the trench build process consists of
depositing 30nm of low pressure chemical vapor deposition (LPCVD)
silicon nitride. This is followed by depositing 200nm of plasma
enhanced chemical vapor deposition (PECVD) tetraethoxysilane (TEOS)
silicon dioxide.

      The wafer is then coated with photoresist and exposed using a
mask which contains a long narrow serpentine with a large pad on each
end. This serpentine intertwines between 2 comb structures which have
their own probing pad.  This serpentine structure has a known length
and width for sheet resistance calculations.  The serpentine is
typically 1um wide and hundreds of microns long.  Photoresist
thickness is typically 1um or greater.  After e...