Resurf structure and LDMOS device

A lateral diffused metal oxide semiconductor (LDMOS) device, comprising:

• a substrate of a first conductivity type;
• an epitaxial layer of a second conductivity type, disposed on the substrate;
• a well region of the first conductivity type, disposed in the epitaxial layer;
• a deep well region of the second conductivity type, disposed in the epitaxial layer;
• a source region of the second conductivity type, disposed in the well region;
• a drain region of the second conductivity type, disposed in the deep well region;
• an isolation structure, disposed on the deep well region;
• a gate, disposed on the epitaxial layer between the drain region and the source region and extending to above a portion of the isolation structure;
• at least one trench insulating structure, disposed in the deep well region below the isolation structure;
• and
• at least one doped region of the first conductivity type, disposed in the deep well region and surrounding a sidewall and a bottom of the trench insulating structure.