High voltage device structure and methods of forming the same

A high-voltage device structure, comprising:

• a high-voltage device disposed over a substrate, wherein the high-voltage device comprises a source region, a drain region, and a gate structure;
• a first guard structure surrounding the source region and the drain region of the high-voltage device, wherein the first guard structure comprises a first pickup region, a first well region, and a first deep well region;
• and
• a first isolation structure disposed between the source region of the high-voltage device and the first pickup region of the first guard structure, wherein the first isolation structure comprises a first conductive layer disposed in a first isolation region.

A high-voltage device structure, comprising:

• a deep well region of a first conductivity type disposed in a substrate;
• a doped region disposed on the deep well region;
• a well region of the first conductivity type surrounding the deep well region and the doped region;
• a source region disposed on the well region;
• a drain region disposed on the doped region;
• and
• a first pickup region disposed on the well region and adjacent at least one side of the drain region, wherein the first pickup region is electrically connected to the source region.