Semiconductor structure and formation method thereof

A method of forming a semiconductor structure, comprising:

• providing a substrate;
• forming a covering layer over a part of the substrate;
• using a first selective deposition process to form an auxiliary layer over a surface of the covering layer;
• forming a first dielectric layer over surfaces of the substrate and the auxiliary layer;
• forming a conductive structure in the first dielectric layer, wherein a top surface of the first dielectric layer is flush with a top surface of the conductive structure;
• forming a second dielectric layer over surfaces of the first dielectric layer and the conductive structure;
• forming a first opening and a second opening, wherein the first opening is located in the second dielectric layer and the first dielectric layer, and the first opening exposes the auxiliary layer, and the second opening is located in the second dielectric layer and the second opening exposes the top surface of the conductive structure;
• and
• forming a first conductive layer in the first opening and forming a second conductive layer in the second opening, wherein a growth rate of a material of the first conductive layer over a surface of the auxiliary layer is higher than a growth rate of the material of the first conductive layer over the surface of the covering layer.