The invention discloses a vertical parasitic PNP device in a
BiCMOS (Bipolar Complementary
Metal-
Oxide-
Semiconductor) process. The vertical parasitic PNP device comprises a collector region, a base region, an emitter region, a P type buried layer and N type
polycrystalline silicon, wherein the buried layer is formed at a shallow trench filed
oxide bottom surrounding the collector region and is in contact with the collector region through a
deep hole formed at the top of the buried layer to lead out a collector
electrode; the N type
polycrystalline silicon is formed at the upper part of the base region and is used for leading out a base
electrode; and the emitter region is composed of a P type
shallow junction formed in the base region and P type
polycrystalline silicon arranged above the base region. The invention also discloses a preparation method of the vertical parasitic PNP device in the
BiCMOS process. The device disclosed by the invention can serve as an
output device in a high-speed high-
gain BiCMOS circuit, and therefore another device choice is provided for the circuit. According to the invention, the area of the device can be reduced effectively, the resistance of the collector
electrode of a PNP
transistor can be lowered, the frequency performance of the device can be improved and the
gain of the device can be enhanced. No extra process condition is required in the preparation method disclosed by the invention, thereby reducing the production cost.