Patent ID: 11961833
Assignee: RICHTEK TECHNOLOGY CORPORATION
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A high voltage device for use as a low-side switch in a power stage of a switching regulator, the high voltage device comprising:
at least one lateral diffused metal oxide semiconductor (LDMOS) device, wherein the LDMOS device includes:
a well, which has a first conductivity type, and is formed in a semiconductor layer;
a body region, which has a second conductivity type, and is formed in the well;
a gate, which is formed on the body region and is connected to the body region; and
a source and a drain, which have the first conductivity type, and are located at different sides out of the gate respectively, wherein the source is located in the body region, and the drain is located in the well; and

a first isolation region, which has the second conductivity type, and is formed in the semiconductor layer, wherein the first isolation region encloses the LDMOS device;
a second isolation region, which has the first conductivity type, and is formed in the semiconductor layer, wherein the second isolation region encloses the first isolation region;
a third isolation region, which has the second conductivity type, and is formed in the semiconductor layer, wherein the third isolation region encloses the second isolation region;
a current limiting device, which is electrically connected to the second isolation region and which is configured to operably suppress a parasitic silicon controlled rectifier (SCR) from being turned on;
wherein part of the body region, which is between the source and a boundary of the body region, and is right below the gate, forms an inversion region which serves as an inversion current channel in an ON operation of the LDMOS device;
wherein part of the well between the body region and the drain is a drift region, which serves as a drift current channel in the ON operation of the LDMOS device.