Semiconductor structure and formation method thereof

A method for fabricating a semiconductor structure, comprising:

• providing a substrate, wherein the substrate includes a shielding region having a first area;
• forming a first shielding layer on the substrate, wherein a first shielding structure is in the first shielding layer of the shielding region;
• a projection of the first shielding structure has a first projection on a surface of the substrate;
• and the first shielding structure has a first density, the first density being a ratio of an area of the first projection over the first area;
• forming a second shielding layer on the first shielding layer, wherein a second shielding structure is in the second shielding layer of the shielding region;
• a projection of the second shielding structure has a second projection on the surface of the substrate;
• the second shielding structure has a second density which is less than the first density, the second density being a ratio of an area of the second projection over the first area;
• and
• forming an electrical interconnection structure, electrically interconnecting the first shielding structure with the second shielding structure and enabling the first shielding structure grounded.