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Introducing Controlled Amounts of Interfacial Oxygen in Si Devices

IP.com Disclosure Number: IPCOM000104364D
Original Publication Date: 1993-Apr-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 86K

Publishing Venue

IBM

Related People

Agnello, PD: AUTHOR [+2]

Abstract

Disclosed is a process to control the amount of oxygen at the interface in a Si-based device. First a deposition system and process is used which introduces very low amounts of oxygen by inadvertent steps in the process, an amount much lower than the desired values in the fabricated structure. Secondly, the deposition is fitted such that oxygen may be deliberately added when desired in a certain portion of the structure, to control the desired amount of oxygen at the interface. This technique has been reduced to practice in the following manner:

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Introducing Controlled Amounts of Interfacial Oxygen in Si Devices

      Disclosed is a process to control the amount of oxygen at the
interface in a Si-based device.  First a deposition system and
process is used which introduces very low amounts of oxygen by
inadvertent steps in the process, an amount much lower than the
desired values in the fabricated structure.  Secondly, the deposition
is fitted such that oxygen may be deliberately added when desired in
a certain portion of the structure, to control the desired amount of
oxygen at the interface.  This technique has been reduced to practice
in the following manner:

     The deposition system to be used employs a load lock (to avoid
inadvertent exposure of the reactor proper to atmospheric oxygen an
water vapor), all welded and metal gasket joined lines, heated lines,
purified gases and gas monitors to measure impurity levels and
careful gas handling procedures to minimize inadvertent oxygen and
water introduction into the system.  The figure shows schematically
the load locked reaction tube and the details of the oxygen and
moisture monitor installation such that the effluent of the reactor
could be monitored.  Not shown in the figure are the provisions to
sample the inlet gases, prior to the reactor (which were provided),
nor are the details of the heated and purified inlet gas lines shown.
With such a system under the conditions of no oxygen added the
following can be achieved:  A silicon wafer was cleaned and HF etched
before being placed in the load lock which is purged with purified
Ar.  The wafer was then heated in purified hydrogen (the measured
oxygen impurity concentration is 5-10 parts per billion (ppb) and the
water impurity concentration is less than 10 ppb) to 650-850ºC
and Si was deposited from dichlorosilane at atmospheric pressure.
THe wafer was removed via the load lock.  With the above procedure
the amount of oxygen at the interface and in the Si film is so low
that no oxygen peaks are apparent above the background level of
10sup(17)/cm sup(2), which is the resolution limit of the Secondary Ion Mass
Spect...