A high voltage lateral Double diffused Metal Oxide Semiconductor (DMOS)
transistor includes a plurality of well regions of a first conductivity
type formed to be spaced out within a well region of a second conductivity
type between a channel region of the first conductivity type and a drain
region of the second conductivity type. Most current is carried through
some portions of the well region of the second conductivity type in which
the well regions of the first conductivity do not appear so that the
current carrying performance of the device is improved. When a bias
voltage is applied to the drain region, the well region of the second
conductivity type is completely depleted at other portions where the well
region of the second conductivity type and the well regions of the first
conductivity type alternately appear so that the breakdown voltage of the
device can be increased. In addition, since the well region of the second
conductivity type can be easily depleted, not only the breakdown voltage
can be increased, but also the impurity concentration of the well region
of the second conductivity type can be increased. Accordingly, the
on-resistance of the device can be decreased.
