A semiconductor device includes a substrate, a source/drain feature, a gate structure, a contact, a gate spacer, and a contact spacer. The source/drain feature is at least partially disposed in the substrate. The gate structure is disposed on the substrate and adjacent to the source/drain feature. The contact is electrically connected to the source/drain feature. The gate spacer is disposed on a sidewall of the gate structure and between the gate structure and the contact. The contact spacer is disposed on the gate spacer and on a sidewall of the contact. An interface is formed between the gate spacer and the contact spacer, and a bottom surface of the contact spacer is in contact with the contact.