Semiconductor device and manufacturing method thereof

A manufacturing method of a semiconductor device, comprising:

• providing a semiconductor substrate;
• forming a hard mask over the semiconductor substrate;
• etching the semiconductor substrate by using the hard mask as an etch mask, wherein the semiconductor substrate is divided into a central region and a peripheral region, and the central region and the peripheral region are separated by a first trench;
• forming a first dielectric layer along a sidewall of the semiconductor substrate in the first trench;
• forming a blocking structure in the first trench, wherein the blocking structure is in a U-shaped;
• and
• filling the first trench with a filling material, wherein the filling material covers the blocking structure and is in contact with the first dielectric layer.

A semiconductor device, comprising:

• a semiconductor substrate comprising a central region and a peripheral region, wherein the central region comprises a plurality of active areas, and the peripheral region is adjacent to the central region;
• and
• an isolation structure between the central region and the peripheral region of the semiconductor substrate, wherein the isolation structure comprises:
• a blocking structure, wherein the blocking structure is in a U-shaped;
• and
• a first insulation structure wrapping the blocking structure, wherein the first insulation structure is made of a first material, the blocking structure is made of a second material, a dielectric constant of the first material is lower than a dielectric constant of the second material.