A method of forming a semiconductor device structure is provided. The method includes forming a masking structure with first openings over a semiconductor substrate and correspondingly forming metal layers in the first openings. The method also includes recessing the masking structure to form second openings between the metal layers and forming a sacrificial layer surrounded by a first liner in each of the second openings. In addition, after forming a second liner over the sacrificial layer in each of the second openings, the method includes removing the sacrificial layer in each of the second openings to form a plurality of air gaps therefrom.