Fin field effect transistor device structure and method for forming the same

A method for forming a fin field effect transistor device structure, comprising:

• forming fin structures over a substrate;
• forming a gate structure across the fin structures;
• forming source/drain epitaxial structures over the fin structures on opposite sides of the gate structure;
• forming a dielectric structure surrounding the source/drain epitaxial structures;
• forming blocking structures between the fin structures;
• depositing contact structures over the fin structures;
• forming a via structure over a top surface of the contact structure and electrically connected to the contact structures;
• removing a top portion of the blocking structures;
• and
• depositing an etch stop layer over the blocking structures, the contact structures, and the via structure, wherein an air gap is formed between the contact structures;
• and
• planarizing the etch stop layer to expose the via structure.

A method for forming a fin field effect transistor device structure, comprising:

• forming a first fin structure and a second fin structure over a substrate;
• forming a gate structure across the first fin structure and the second fin structure;
• growing a first source/drain epitaxial structure over the first fin structure and a second source/drain epitaxial structure over the second fin structure over opposite sides of the gate structure;
• depositing a dielectric layer covering the first source/drain epitaxial structure and the second source/drain epitaxial structure;
• forming a blocking structure between the first source/drain epitaxial structure and the second source/drain epitaxial structure;
• removing the dielectric layer over the first source/drain epitaxial structure and the second source/drain epitaxial structure to expose the first source/drain epitaxial structure and the second source/drain epitaxial structure;
• forming a first contact structure over the first source/drain epitaxial structure and a second contact structure over the second source/drain epitaxial structure;
• recessing the blocking structure between the first source/drain epitaxial structure and the second source/drain epitaxial structure;
• depositing an etching stop layer over the first contact structure, the second contact structure, and the blocking structure;
• forming a hard mask layer formed over the etching stop layer;
• and
• forming a via structure through the hard mask layer and the etching stop layer,
• wherein an air gap is formed below the etching stop layer and between the first contact structure and the second contact structure, and wherein the via structure is in direct contact with the first contact structure.