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We describe high-voltage SJ SOI-LDMOSFETs which have a trench oxide in
the drift region.
With the proposed device structure a reduction of the on-resistance
of the 
-drift layer can be achieved.
The BV and the specific on-resistance of the suggested
devices as a function of the trench oxide depth, the 
-column width, and the
doping are studied. We confirm that the specific on-resistance
of the device proposed is lower than that of conventional SOI-LDMOSFETs,
and the drift length is reduced to 65% compared to conventional devices.
To obtain the best trade-off between
and the BV, we suggest a SJ
SOI-LDMOSFET which has an extra -column and a trench oxide in the drift region.
The extra -column is doped to achieve a balanced charge condition which means that
the net depletion layer charge is zero. The trench oxide in the -column helps
to reduce the drift length without further decreasing the conduction area
(only the -column contributes to the current conduction).
The
of the proposed structure
is effectively reduced by the SJ concept together with the trench
oxide. The SJ helps to increase the doping concentration of the -drift
layer, and the trench oxide in the drift allows to reduce the device size.
Lowering
without degrading the BV gives rise to a reduction
in silicon area, which supports the economic fabrication of
smart power devices.
Jong-Mun Park 2004-10-28