Metal oxide semiconductor (mos) device and manufacturing method thereof

A metal oxide semiconductor (MOS) device, formed in a substrate with an upper surface, the MOS device comprising:

• an isolation region, which is formed on the upper surface for defining an operation region;
• a well region with a first conductive type, which is formed beneath the upper surface in the substrate;
• a gate, which is formed on the upper surface, wherein the gate is located in the operation region from top view, and the gate includes:
• a dielectric layer, which is formed on the upper surface and in contact with the upper surface;
• a stack layer, which is formed on the dielectric layer;
• and
• a spacer layer, which is formed outside side walls of the stack layer, wherein the stack layer divides the operation region into a first side and a second side;
• a lightly-doped-source (LDS) with the first conductive type, which is formed at the first side beneath the upper surface of the substrate, wherein at least part of the LDS overlaps the stack layer from a top view;
• a lightly-doped-drain (LDD) with a second conductive type, which is formed at the second side beneath the upper surface of the substrate;
• a source with the second conductive type, which is formed at the first side beneath the upper surface of the substrate, wherein part of the source overlaps the spacer layer at the first side from the top view;
• and
• a drain, with the second conductive type, which is formed at the second side beneath the upper surface of the substrate.