Semiconductor device structure having air gap and method for forming the same

A semiconductor device structure, comprising:

• a fin structure extending from a semiconductor substrate;
• a first gate structure, a second gate structure, and a third gate structure across the fin structure;
• a first source/drain contact structure formed between and adjacent to the second gate structure and the third gate structure;
• a second source/drain contact structure separated from the first source/drain contact structure by the third gate structure;
• and
• a first insulating cap structure formed between the first gate structure and the second gate structure, wherein the first insulating cap structure is separated from the fin structure by a first inverted T-shaped air gap, and wherein a portion of the first inverted T-shaped air gap is extended into the first insulating cap structure.

A semiconductor device structure, comprising:

• a first gate electrode formed over a semiconductor substrate and having a first sidewall and a second sidewall opposite to the first sidewall;
• a first insulating cap structure formed adjacent to the first sidewall of the first gate electrode and separated from the semiconductor substrate by a first inverted T-shaped air gap;
• and
• a second insulating cap structure formed adjacent to the second sidewall of the first gate electrode and separated from the semiconductor substrate by a second inverted T-shaped air gap, wherein a height of the second inverted T-shaped air gap is substantially equal to a height of the first inverted T-shaped air gap and greater than a height of the first gate electrode.