A bipolar transistor in which the occurrence of Kirk effect is suppressed when
a high current is injected into the bipolar transistor and a method of fabricating
the bipolar transistor are described. The bipolar transistor includes a first collector
region of a first conductive type having high impurity concentration, a second
collector region of a first conductive type which has high impurity concentration
and is formed on the first collector region, a base region of a second conductive
type being formed a predetermined portion of the second collector region, and an
emitter region of a first conductive type being formed in the base region. The
bipolar transistor further includes the third collector region, which has higher
impurity concentration than the second collector region, at the bottom of the base
region. Therefore, it is possible to prevent the base region from extending toward
the second collector region due to the third collector region when a high current
is injected into the bipolar transistor, thereby improving the capability of driving
a current of the bipolar transistor and preventing the occurrence of Kirk effect
even during the injection of a high current.
