Air spacer formation with a spin-on dielectric material

A method, comprising:

• forming a first spacer layer on a sidewall of a gate structure;
• forming a sacrificial spacer layer adjacent to the first spacer;
• forming a second spacer layer adjacent to the sacrificial spacer layer;
• forming a source/drain (S/D) contact structure, wherein the first spacer layer, the sacrificial spacer laver, and the second spacer layer are between the S/D contact structure and the gate structure;
• selectively etching a top portion of one or more of the first spacer layer, the sacrificial spacer layer, and the second spacer layer to form a recess;
• removing the sacrificial spacer layer to form an air gap between the first spacer layer and the second spacer layer;
• spinning a dielectric layer on the air gap, the first spacer layer, and the second spacer layer to fill in the recess and seal the air gap, wherein the dielectric layer comprises raw materials for a spin-on dielectric material;
• treating the raw materials in the dielectric layer to form the spin-on dielectric material;
• and
• polishing the dielectric layer to form a spin-on dielectric structure.

A method, comprising:

• forming an intermediate spacer structure on sidewalls of a gate structure and a gate capping structure, wherein the intermediate spacer structure comprises a first spacer layer, a second spacer layer, and a sacrificial spacer layer between the first and second spacer layers, and wherein the first spacer layer is in contact with the gate structure and the gate capping structure;
• forming a S/D contact structure in contact with the second spacer layer;
• selectively etching a top portion of the sacrificial spacer layer and a top portion of at least one of the first spacer layer and the second spacer layer to form a recess;
• removing the sacrificial spacer layer to form an air gap between the first spacer layer and the second spacer layer;
• depositing a dielectric layer in the recess with a spin-on process to seal the air gap, wherein the dielectric layer comprises raw materials for a spin-on dielectric material;
• treating the raw materials in the dielectric layer to form the spin-on dielectric material;
• and
• polishing the dielectric layer to co-planarize top surfaces of the spin-on dielectric material, the gate capping structure, and the S/D contact structure.