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Method of Determining the Selectivity During the Deposition Of Silicon On Si/SiO2 Surfaces

IP.com Disclosure Number: IPCOM000121646D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 36K

Publishing Venue

IBM

Related People

Euen, W: AUTHOR [+3]

Abstract

In 4 Mb DRAMs, the trench capacity and the adjacent diffusion are electrically connected by depositing an Si layer. In the ideal case, the silicon is deposited in monocrystalline form only on silicon surfaces (desirable), which means that there is no deposition on SiO2/ Si3N4 surfaces.

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Method of Determining the Selectivity During the Deposition Of Silicon
On Si/SiO2 Surfaces

      In 4 Mb DRAMs, the trench capacity and the adjacent
diffusion are electrically connected by depositing an Si layer.  In
the ideal case, the silicon is deposited in monocrystalline form only
on silicon surfaces (desirable), which means that there is no
deposition on SiO2/ Si3N4 surfaces.

      The degree of selectivity during the deposition on different
surfaces, which cannot be determined by existing methods immediately
after silicon deposition, is a direct measure of the yield to be
expected, as, for example, silicon deposited on SiO2 produces shorts.

      The method described below uses two principles for this
purpose:
      1.   Processing blanket oxidized wafers by selective Si
deposition
           As a result of inadequate selectivity (<100%), silicon is
also grown in the form of needle-shaped protrusions on SiO2 surfaces,
as shown by SEM.
      2.   Forming a MOS structure for BDV (breakdown voltage)
measurements
           By depositing Al dots on the wafer thus processed for
forming a MOS structure, it is possible to examine how the
needle-shaped Si protrusions affect the breakdown characteristics of
the oxide.
          It has been found that undesired Si deposition locally
increases the field strength and degrades the breakdown voltage and
the BDV yield, respectively.

      Thus, the selectivity of silico...