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Electrical effects of anodic bonding on silicon dioxide situated in Pyrex cavities

Abstract

We have investigated the effects of anodic bonding on silicon dioxide
by measuring MOS capacitors situated in Pyrex cavities. We used two
different cavity depths, giving 1 µm or 200 µm vertical distance
between the gate electrode and the Pyrex. After bonding, we found that
the flat-band voltage of the capacitors situated in 1 µm deep cavities
had shifted towards more negative values. The shift corresponded to
6.6E11cm-2 - 9.0E11cm-2 increase in oxide charge density. The
capacitors situated in 200 µm deep cavities showed a slight shift in
the opposite direction, which we attribute to thermal annealing of
oxide fixed charge. The values of the flat-band voltages remained
stable after nine months of storage. In addition, we observed that the
current between the gate and the substrate contact had increased after
bonding. The increase was by a factor between 20 and 150, depending
both on cavity depth and gate geometry. The current in the capacitors
with 200 µm vertical distance to the Pyrex had returned to the initial
level after nine months of storage. The capacitors with 1 µm distance
to the Pyrex still had enhanced currents. Some explanations for our
observations are suggested.

Category

Academic article

Language

English

Author(s)

  • Kari Schjølberg-Henriksen
  • Anders Bror Hanneborg
  • Geir Uri Jensen
  • Adriana C. Lapadatu
  • Henrik Jakobsen

Affiliation

  • SINTEF Digital / Microsystems and Nanotechnology
  • University of Oslo
  • Unknown

Year

2002

Published in

Journal of the Electrochemical Society

ISSN

0013-4651

Publisher

IOP Publishing

Volume

149

Issue

8

Page(s)

G497 - G503

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