Texas Instruments Corporation

Jun Wang

Shuming Xu

Jacek Korec

Frank Alexander Baiocchi

Haian Lin

Boyi Yang

An integrated semiconductor transistor chip for use in a buck converter includes a high side transistor formed on the chip and comprising a laterally diffused metal oxide semiconductor (LDMOS) transistor and a low side transistor formed on the chip and comprising a source down metal oxide semiconductor field effect transistor (MOSFET). The chip also includes a substrate of the chip for use as a source for the low side transistor and an n-doped well for isolation of the high side transistor from the source of the low side transistor.

Monolithically integrated transistors for a buck converter using source down MOSFET

Capacitors and methods of forming semiconductor device capacitors are disclosed. Trenches are formed to define a capacitor bottom plate in a doped upper region of a semiconductor substrate, a dielectric layer is formed conformally over the substrate within the trenches, and a polysilicon layer is formed over the dielectric layer to define a capacitor top plate. A guard ring region of opposite conductivity and peripheral recessed areas may be added to avoid electric field crowding. A central substrate of lower doping concentration may be provided to provide a resistor in series below the capacitor bottom plate. A series resistor may also be provided in a resistivity region of the polysilicon layer laterally extending from the trenched area region. Contact for the capacitor bottom plate may be made through a contact layer formed on a bottom of the substrate. A top contact may be formed laterally spaced from the trenched area by patterning laterally extended portions of one or more of the dielectric, polysilicon and top metal contact layers.

Capacitors and methods of forming

A power MOSFET is formed in a semiconductor device with a parallel combination of a shunt resistor and a diode-connected MOSFET between a gate input node of the semiconductor device and a gate of the power MOSFET. A gate of the diode-connected MOSFET is connected to the gate of the power MOSFET. Source and drain nodes of the diode-connected MOSFET are connected to a source node of the power MOSFET through diodes. The drain node of the diode-connected MOSFET is connected to the gate input node of the semiconductor device. The source node of the diode-connected MOSFET is connected to the gate of the power MOSFET. The power MOSFET and the diode-connected MOSFET are integrated into the substrate of the semiconductor device so that the diode-connected MOSFET source and drain nodes are electrically isolated from the power MOSFET source node through a pn junction.

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Bethlehem, PA, United States of America

Jun Wang