Integrated complementary low voltage rf-ldmos

Abstract

Complementary RF LDMOS transistors have gate electrodes over split gate oxides. A source spacer of a second conductivity type extends laterally from the source tap of a first conductivity type to approximately the edge of the gate electrode above the thinnest gate oxide. A body of a first conductivity type extends from approximately the bottom center of the source tap to the substrate surface and lies under most of the thin section of the split gate oxide. The source spacer is approximately the length of the gate sidewall oxide and is self aligned with gate electrode. The body is also self aligned with gate electrode. The drain is surrounded by at least one buffer region which is self aligned to the other edge of the gate electrode above the thickest gate oxide and extends to the below the drain and extends laterally under the thickest gate oxide. Both the source tap and drain are self aligned with the gate side wall oxides and are thereby spaced apart laterally from the gate electrode.

Description

FIELD OF THE INVENTION[0001]This invention relates to power MOSFETs, and more particularly, to low power lateral complementary power MOSFETs.BACKGROUND OF THE INVENTION[0002]The widespread use of personal communication products, such as cell phones and wireless LANs, has created a demand for semiconductor devices which can provide certain operational characteristics specific to these devices. One of these operational characteristics relates to the power dissipated in the semiconductor devices. The conventional method to reduce the power dissipation is to use a power supply voltage of three volts or less. However, certain portions of the electronics, such as the RF transmitters, require power devices that can handle higher voltages and currents than are not present in the rest of the electronic circuitry. This requirement is exacerbated by the demand for ever smaller products thus providing a strong incentive for combining complementary power devices on the same substrate as other po...

AI Technical Summary

Problems solved by technology

However, certain portions of the electronics, such as the RF transmitters, require power devices that can handle higher voltages and currents than are not present in the rest of the electronic circuitry.

However such drift regions increase device resistance and take up space on a semiconductor chip thus requiring a significantly larger chip area than needed for convention MOSFETs.

In addition, most of these prior art LDMOS transistors have relatively low DC transconductance that also is significantly degraded in the frequency ranges used in many of the personal communication products, have power loss in the device due to capacitances, junction leakage and substrate loss, and can have reliability problems arising from the hot carrier effect.

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