High Voltage Metal Oxide Semiconductor Device and Method for Making Same

A high voltage metal oxide semiconductor (HVMOS) device comprising:

• a substrate;
• a gate structure on the substrate;
• an N-type well in the substrate, which defines a device region from top view;
• a first P-type drift region in the N-type well;
• a P-type source in the N-type well;
• a P-type drain in the first P-type drift region, the P-type drain being separated from the gate structure by a part of the first P-type drift region;
• and
• a first P-type dopant region covering a part of a junction of the P-type drain and the first P-type drift region but not covering all the device region, wherein the first P-type dopant region is formed by implanting a P-type dopant for reducing an ON resistance of the HVMOS device.

A method for making a high voltage metal oxide semiconductor (HVMOS) device, comprising:

• providing a substrate;
• forming a first conductive type well in the substrate, which defines a device region from top view;
• forming a second conductive type drift region in the first conductive type well;
• forming a gate structure on the substrate;
• forming a second conductive type source in the first conductive type well;
• forming a second conductive type drain in the drift region, the second conductive type drain being separated from the gate structure by a part of the drift region;
• and
• forming a P-type dopant region below the substrate surface by implanting a P-type dopant, for adjusting a threshold voltage of the HVMOS device, and in the meanwhile enhancing a breakdown voltage or reducing an ON resistance thereof.