The present disclosure provides a semiconductor die structure with air gaps for reducing capacitive coupling between conductive features and a method for preparing the semiconductor die structure. The semiconductor die structure includes a substrate; a first supporting backbone disposed on the substrate; a second supporting backbone disposed on the substrate; a first conductor block disposed on the first supporting backbone; a second conductor block disposed on the second supporting backbone; a third conductor block disposed above the substrate and connected to the first conductor block and the second conductor block; and an air gap structure disposed between the first conductor block, the second conductor block, and the third conductor block, wherein the air gap structure comprises an air gap and a liner layer enclosing the air gap.