Manufacturing method of semiconductor device including conductive structure

A manufacturing method of a semiconductor device includes the following steps. A semiconductor substrate with gate structures formed thereon is provided. A source/drain region is formed in the semiconductor substrate and formed between the gate structures. A dielectric layer is formed on the source/drain region and located between the gate structures. An opening penetrating the dielectric layer on the source/drain region is formed. A lower portion of a first conductive structure is formed in the opening. A dielectric spacer is formed on the lower portion and on an inner wall of the opening. An upper portion of the first conductive structure is formed in the opening and on the lower portion. The dielectric spacer surrounds the upper portion of the first conductive structure. The first conductive structure is formed by two steps for forming the dielectric spacer surrounding the upper portion and improving the electrical performance of the semiconductor device.