Integrated lateral high-voltage metal oxide semiconductor field effect transistor
View Patent ↗The present invention relates to integration of a lateral high-voltage metal oxide semiconductor field effect transistor (LHV-MOSFET) with other circuitry on a semiconductor wafer, which may be fabricated using low-voltage foundry technology, such as a low-voltage complementary metal oxide semiconductor (LV-CMOS) process. The other circuitry may include low-voltage devices, such as switching transistors used in logic circuits, computer circuitry, and the like, or other high-voltage devices, such as a microelectromechanical system (MEMS) switch. The source to drain voltage capability of the LHV-MOSFET may be increased by using an intrinsic material between the source and the drain. The gate voltage capability of the LHV-MOSFET may be increased by using an insulator material, such as a thick oxide, between the gate and the channel of the LHV-MOSFET.
1. A semiconductor wafer comprising:
a first insulator layer;
a first semiconductor device layer formed over the first insulator layer and comprising;
a source, and a source extension adjacent to the source;
a channel formed between the source and the drain;
a drain, and a drain extension adjacent to the drain; and
first intrinsic material between the source and the drain, such that the first intrinsic material has a resistivity greater than about one ohm·centimeter and the source, the drain, and the first intrinsic material form a lateral high-voltage metal oxide semiconductor field effect transistor (LHV-MOSFET); and
a second insulator layer formed over the first semiconductor device layer; and wherein:
the source comprises highly-doped semiconductor material having a carrier concentration greater than about 10 18 cm −3 ;
the drain comprises highly-doped semiconductor material having a carrier concentration greater than about 10 18 cm −3 ;
the channel comprises doped semiconductor material having a carrier concentration less than about 10 18 cm −3 ;
the source extension comprises doped semiconductor material having a carrier concentration less than about 10 18 cm −3 ; and
the drain extension comprises doped semiconductor material having a carrier concentration less than about 10 18 cm −3 .
2. The semiconductor wafer of claim 1 wherein a breakdown voltage between the drain and the source is greater than about 20 volts.
3. The semiconductor wafer of claim 1 wherein a breakdown voltage between the drain and the source is greater than about 50 volts.
4. The semiconductor wafer of claim 1 wherein a reverse breakdown voltage of at least one of a first diode junction formed from highly-doped N-type semiconductor material adjacent to doped P-type semiconductor material and a second diode junction formed from highly-doped P-type semiconductor material adjacent to doped N-type semiconductor material is less than about 20 volts.
5. The semiconductor wafer of claim 1 further comprising a Silicon-on-Insulator (SOI) wafer having a substrate.
6. The semiconductor wafer of claim 5 wherein an SOI insulator layer is formed over the substrate, an SOI device layer is formed over the SOI insulator layer, the SOI insulator layer provides the first insulator layer, and the SOI device layer provides the first semiconductor device layer.
7. The semiconductor wafer of claim 5 wherein an SOI insulator layer is formed over the substrate, an SOI device layer is formed over the SOI insulator layer, an epitaxial layer is formed over the SOI device layer, and the epitaxial layer provides the first semiconductor device layer.
8. The semiconductor wafer of claim 1 wherein the LHV-MOSFET further comprises a gate formed over the second insulator layer.
9. The semiconductor wafer of claim 8 wherein the gate comprises poly-Silicon.
10. The semiconductor wafer of claim 8 wherein the second insulator layer is a local oxidation of Silicon (LOCOS) layer.
11. The semiconductor wafer of claim 8 wherein a breakdown voltage between the gate and the channel is greater than about 20 volts.
12. The semiconductor wafer of claim 8 wherein a breakdown voltage between the gate and the channel is greater than about 50 volts.
13. The semiconductor wafer of claim 8 further comprising second intrinsic material between the source and the channel, wherein the first intrinsic material is between the drain and the channel.
14. The semiconductor wafer of claim 8 wherein the channel comprises doped semiconductor material.
15. The semiconductor wafer of claim 1 wherein:
the source comprises highly-doped N-type semiconductor material;
the drain comprises highly-doped N-type semiconductor material;
the channel comprises doped P-type semiconductor material;
the source extension comprises doped N-type semiconductor material; and
the drain extension comprises doped N-type semiconductor material.
16. The semiconductor wafer of claim 1 wherein:
the source comprises highly-doped P-type semiconductor material;
the drain comprises highly-doped P-type semiconductor material;
the channel comprises doped N-type semiconductor material;
the source extension comprises doped P-type semiconductor material; and
the drain extension comprises doped P-type semiconductor material.
17. The semiconductor wafer of claim 1 wherein the LHV-MOSFET is laterally isolated from at least one other device in the first semiconductor device layer using deep trench isolation.
18. The semiconductor wafer of claim 1 further comprising a microelectromechanical system (MEMS) switch.
19. The semiconductor wafer of claim 18 wherein the LHV-MOSFET is adapted to provide an actuation signal to an actuator of the MEMS switch.