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Carbon Monoxide Addition during High Temperature Annealing of SI-SIO2. Structures

IP.com Disclosure Number: IPCOM000112793D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Raider, S: AUTHOR

Abstract

Carbon is a common impurity in crystalline silicon. The average carbon concentration in bulk silicon is typically low

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 64% of the total text.

Carbon Monoxide Addition during High Temperature Annealing of SI-SIO2.
Structures

      Carbon is a common impurity in crystalline silicon.  The
average carbon concentration in bulk silicon is typically low

(~ 10 sup(16)cm(-3)) but the concentration of carbon at
local sites near a silicon surface can be significantly higher due to
contamination from external sources, e.g., through handling and
processing.  At elevated temperatures, this carbon nucleates at
crystalline silicon defect sites or heterogeneously precipitates with
oxygen or other impurities to form localized precipitates near the
surface or at a Si-SiO&sub2.  interface.  In an oxidizing ambient,
carbon nucleates at sites below a silicon surface.  However, at the
silicon surface or interface, carbon precitation competes with carbon
oxidation process.

      During annealing of Si-SiO&sub2.  structures in non-oxidizing
ambients, the carbon precipitates with silicon dioxide films.  The
carbon and silicon dioxide are consumed and a gaseous product,
presumably CO, is evolved.  The gaseous molecule, CO, diffuses from
the interface to the ambient through the silicon dioxide film.  The
overall reaction is:

     2 C + SiO&sub2.  = 2 CO(g) + Si

      Similar annealing with carbon impurities in silicon at
temperatures down to 700ºC degrades the electrical properties of
MOS devices.

      The potential for carbon contamination is present at nearly all
stages of processing.  Contamination can...