Double diffused metal oxide semiconductor device and manufacturing method thereof

A double diffused metal oxide semiconductor (DMOS) device, comprising:

• a first conductive type substrate, which has an upper surface;
• a second conductive type high voltage well, which is formed in the substrate below the upper surface;
• a gate, which is formed on the upper surface, wherein at least part of the gate is located in the high voltage well from top view, and the gate has a first side and a second side opposite to each other in a vertical direction;
• a first conductive type body region, which is formed in the high voltage well below the upper surface, wherein at least part of the body region is located outside the first side;
• a source and a drain with the second conductive type, which are formed below the upper surface outside the gate, the source being located in the body region outside the first side, and the drain being located outside the second side, wherein the drain and the gate are separated by the high voltage well, and when the DMOS device turns ON, a lateral channel is formed between the source and the drain below the upper surface;
• a first conductive type body electrode, which is formed in the body region below the upper surface as an electrical contact of the body region;
• and
• a first conductive type floating region, which is formed in the body region below the upper surface, wherein the floating region is electrically floating and electrically isolated from the source and the gate.